Background

To achieve optimal athletic performance at select time points relative to the competition schedule, strength (e.g., powerlifting, weightlifting, strongman/woman) and physique (e.g., bodybuilding) athletes will participate in strategically-planned resistance exercise training, organized in a cyclic manner [1, 2]. Such training typically involves undertaking periods of challenging training above the habitual level, designed to invoke a physiological adaptation, and periods of reduced training stress, designed to reduce fatigue and mitigate the risk of maladaptation [3]. Indeed, short-term periods of challenging training (facilitated through an increase in training volume or intensity) followed by a period of reduced training stress can lead to improved performance. However, continuous periods of challenging resistance exercise training without enough recovery can disturb the athlete’s physical and psychological well-being, leading to non-functional overreaching (NFOR) or theoretically the overtraining syndrome (OTS) [4,5,6]. Periods of reduced training stress involve a standardized decrease in the quantity of training [7] and can occur either within the overall training macrocycle (e.g., during the off-season), between or during training mesocycles (e.g., lower training stress weeks), or within a training microcycle (e.g., easier training sessions) [8].

Strength athletes often participate in tapering; a period of reduced training stress in the days/weeks prior to a competition, designed to optimize specific fitness characteristics, i.e., peaking [9]. Previous research has indicated that as many as 87–99% of competitive strength athletes incorporate a taper into their programme [10, 11]. In sports such as weightlifting and powerlifting, tapering involves a reduction in training volume while maintaining or slightly reducing training intensity [11, 12] and is generally undertaken for a period of ~ 7 days, with the final training session taking place 4 ± 2 days prior to the competition date [12, 13]. Unlike strength sports, physique sports athletes do not normally incorporate a taper into their training programme [14]. Instead, these athletes will maintain normal resistance exercise training while manipulating energy intake, macronutrient composition, hydration levels, and general physical activity levels (e.g., increased cardiovascular exercise) in the days prior to competition to achieve peak aesthetic condition [1, 14]. The general non-use of tapering in physique sports is likely due to the emphasis on aesthetic condition rather than athletic performance [1, 15].

The terms “regeneration microcycles,” “lighter weeks,” “unloading weeks,” “restitution/recovery weeks,'' and “deloading” have all been used to describe phases of reduced training stress that occur across the overall training programme, but not immediately prior to competition [16,17,18,19,20,21]. The objective of these training phases is to mitigate fatigue, promote recovery, and reduce the risk of NFOR/OTS [16,17,18]. Unlike the taper, the objective of these phases is not to achieve peak performance, but to enhance preparedness for the subsequent training cycle so that the athlete can “reload” and “push again.” [22]. Although the terminology is often used interchangeably by strength and physique coaches, tapering can, therefore, be differentiated from other phases of reduced training stress by both positionality and overall objective [22].

Although no clear consensus definition exists, deloading has been described as a short-term period of reduced training volume and intensity designed to mitigate fatigue and improve training outcomes [21]. To date, there is no research that has objectively reported the prevalence of deloading within strength or physique sports. However, its utilization within strength and physique sports is ubiquitous [22]. Deloading is most likely to be integrated into the athlete’s training programme at the end of each training mesocycle or following an “impact microcycle” e.g., a planned overreaching microcycle [20, 22]. Deloading is generally undertaken every 4–6 weeks for a period of ~ 7 days, although some deloads might range in duration from a singular training session to 2 weeks [22]. During a deloading phase, strength and physique coaches will normally decrease training volume by reducing the number of repetitions completed within a set, the number of sets completed within a training session, or a combination of these strategies [20, 22]. Coaches might also reduce the overall intensity of effort by decreasing the percentage of one-repetition maximum (1-RM) or stopping sets further from muscular failure (i.e., increasing repetitions in reserve). Additionally, exercise selection and configuration might be altered by the coach to reduce training monotony and “change things up” [22]. Overall, empirical research investigating the organization of training variables during deloading is both disparate and heterogeneous, and it is evident that coaches approach the implementation of deloading in a pragmatic and individualized way [22]. Therefore, more research is required to assist both practitioners and sports scientists better understand the factors that influence the design and integration of deloading into strength and physique sport training programmes.

The value of coaches’ experiential knowledge has been neglected in traditional sports science and sport coaching research, resulting in a considerable gap between science and good practice [23]. This might be, in part, due to the complexity of studying athletic populations in situ using classical empirical research designs [24]. However, without guidance from experienced coaches and practitioners, research may not fully elucidate the complicated, multifactorial nature of resistance exercise training prescription. Consequently, improving communication between experimental research and applied environments will foster robust coaching practices, particularly in under-investigated domains such as deloading, where the existing literature is limited [22].

To gain expert consensus on a novel topic within sports science, the Delphi method has previously been utilized [25,26,27,28,29]. This method involves a panel of experts responding anonymously to a series of iterative questionnaires, with feedback from respondents used between rounds to reach a consensus within the group [30, 31]. Given the paucity of research investigating deloading (and the importance of understanding its utility within strength and physique sports), a Delphi method is considered an appropriate methodological tool to enhance knowledge in this domain. Deloading represents a novel area of research, therefore, the aim of this study was to utilize a Delphi method to establish a set of design principles for the integration of deloading into strength and physique sports training programmes.

Methods

Study Design

An online-Delphi study utilizing three iterative rounds was undertaken [32]. Each round included an ad-hoc questionnaire which was developed and administered using a commercial survey provider (Qualtrics©, Provo, Utah, United States). To uphold rigour throughout the Delphi process, the authors selected the exclusion and inclusion criteria for sampling ‘experts’, the thresholds for consensus, the number of rounds, and the analytical approach before recruiting participants [33]. In making these decisions, the authors were informed by a pragmatic approach that addressed the research aims centrally, emphasizing the transferability of findings to coaching practice in strength and physique sports environments, and shared meaning and communication in disseminating new knowledge [34].

Panel Selection

Coaches with expertise in strength and/or physique sports were selected for this study. Purposive sampling was used to recruit participants that were associated with contacts from coaching science and strength and conditioning networks and via social media. To be included in the expert panel, coaches were required to have accreditation/certification from a relevant governing body (e.g., National Strength and Conditioning Association (NSCA), United Kingdom Strength and Conditioning Association (UKSCA)) or a university degree in a related subject area (e.g., Sport and Exercise Science), as well as > 3 years of experience coaching either a strength or physique sport(s). For this study, “strength sports” included weightlifting, powerlifting, and strongman/woman. “Physique sports” comprised all forms of bodybuilding (e.g., Classic, Physique, Figure, Bikini). The choice of sports included in each category was based on previous strength and physique sports research [22].

Unlike experimental studies that use statistical power to determine appropriate sample sizes, the sample size in Delphi studies is dependent on the dynamics of the group in reaching consensus, with 10–18 expert respondents considered optimal for consensus to be achieved [35,36,37]. Sixty participants were invited to participate, with 34 completing the first round (56.7% response rate), 29 of 34 completing the second round (85.3% response rate) and 21 of 29 completing the third round (72.4% response rate). Table 1 outlines the panel demographics. Ethical approval was granted by the university ethics committee of the lead author [ER45112574] in accordance with the principles of the Declaration of Helsinki [38]. All participants provided informed written consent prior to taking part in the study.

Table 1 Participant demographics
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Procedure

As considered optimal to reach consensus, the online-Delphi procedure sought to reach consensus after three rounds [39]. Participants were required to complete the questionnaire for the preceding round to progress onto subsequent rounds.

Round 1: To afford observation of coaches’ experiences and perceptions [40] the first round used open-ended, free-text questions. Fifteen open-ended questions were formulated based on findings from peer-reviewed literature on deloading [22]. The wording of these open-ended questions was informed by the lower-order themes, higher-order themes, and in-text quotations from Bell et al. [22]. Four categories were used to organize the open-ended questions: 1: General Perceptions of Deloading; 2: Potential Applications of Deloading; 3: Designing and Implementing Deloading Training; and 4: Creating an Inclusive Deloading Training Environment. After developing these initial open-ended questions, the lead author met with the other authors to discuss and cross-reference the appropriateness of all questions to the research aim. This afforded dialogue via a collaborative and reflexive working environment where suggestions and ideas from each author listed in the by-line were appraised critically before being integrated into question development where relevant. Questions were either accepted without revisions, developed to omit bias in language or removed from the final question pool. This process enhanced uniformity in question development by ensuring that the language remained as close to the original wording of the concepts and findings outlined in Bell et al. [22] (Fig. 1) [41]. A secure email link, which remained open for four weeks, was used to distribute the online questionnaire for the first round. The list of open-ended questions in the first round is available in the Additional file 1.

Fig. 1
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Adapted from Strafford et al.

Delphi Procedure. [28]

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Microsoft Excel (Version 19) was used to analyze responses from the first round via a two-stage reflexive thematic analysis [42, 43]. A pragmatic approach to reflexive thematic analysis was selected, including deductive and inductive approaches [42,43,44]. The first coding stage was a deductive analysis, where free-text responses from the open-ended questions were grouped into four dimensions (General Perceptions of Deloading, Potential Applications of Deloading Training, Designing and Implementing Deloading Training, Creating an Inclusive Deloading Training Environment). The lead author undertook this first coding stage, which included reading the free-text responses multiple times to identify language relating to each dimension. Peer consultation was employed after this first coding stage, where the authorship independently read the responses from the first round and then engaged in open discussion on the initial dimensions determined by the lead author.

By aligning with pragmatism, the authors recognized that knowledge could not be “theory-free” in that knowledge can be both explicit (as with a theoretical understanding of the subject) and implicit (as with knowledge of how to do things from experience) [45]. Therefore, after data were organized into the three dimensions, a second coding stage was undertaken, consisting of deductive and inductive analyses [46]. This reflexive and collaborative approach to the thematic analysis process was used to gain a more nuanced and richer interpretation of the data rather than gain consensus on meaning [43]. Initial codes generated from the reflexive thematic analysis of first-round responses were grouped into higher-order and lower-order themes relating to study aims. Next, codes that could have been classified into multiple themes were grouped into the theme that best fit. In 4 dimensions, 14 higher-order and 138 lower-order themes were highlighted from the reflexive thematic analysis of free-text responses.

Round 2: The lead author used the language from the first round of free-text responses and the higher- and lower-order themes from the reflexive thematic analysis to develop 138 short statements which were organized into four dimensions: (1) General Perceptions of Deloading, (2) Potential Applications of Deloading Training, (3) Designing and Implementing Deloading Training, (4) Creating an Inclusive Deloading Training Environment. Developing these short statements consisted of the lead author writing one idea per statement as an action to ensure minimum overlap with other items and omit ambiguity [47]. The research team met again to discuss the appropriateness of each statement for addressing the research aims. Draft statements were refined where appropriate to ensure that wording remained as faithful as possible to the original wording of the participants’ free-text responses [41]. For uniformity, statements were either accepted as presented by the lead author, modified to remove bias in language, or deleted (Fig. 1). The open-ended questions in the second and third rounds are available in the Additional file 1.

A secure email link, which remained open for two weeks, was used to distribute the online questionnaire for the second round. Participants were instructed to rate each statement using a four-point Likert scale as either: strongly agree, agree, disagree, or strongly disagree [37]. As a pragmatic decision, an additional option of ‘don’t know’ was also included to afford participants the opportunity to accurately report if they did not have an opinion on a specific statement, rather than it being a requirement to give a substantive perspective option [48]. Raw response data were analyzed descriptively using absolute and relative frequencies.

Round 3: For the third and final round, panellists who responded to the second round received personalized online questionnaires via a secure email link that remained open for two weeks. Each questionnaire included the participant’s individual response from the second round, along with a summary of the group responses as a relative frequency. Taking this approach ensured that participants had the opportunity to revise their answers from the second round if they wished to do so [28]. In that, only statements that reached consensus in the third round and final were used establish a set of design principles for the integration of deloading into strength and physique sports training programmes. Raw response data were analyzed descriptively using absolute and relative frequencies.

Criteria for Consensus: A wide range of consensus levels from 50 to 80% have been used in previous Delphi studies [30]. Following formal consultation with the authorship team and through consultation with previous peer-reviewed work, the consensus was defined as ≥ 70% of the panel agreeing/strongly agreeing or disagreeing/strongly disagreeing with a statement in the third round [37]. All ‘don’t know’ responses were excluded from the analysis to ensure that each statement’s reported percentage agreement or disagreement represented the consensus among panellists who believed they held a firm view [49]. Consensus was considered stable if the variance between the second and third round response varied by ≤ 10%, as recommended by Duffield [50].

Results

Tables 2, 3, 4, 5 provide an overview of the Delphi statements, including those that reached consensus in the second and third rounds. Findings from the third round were used to develop the recommendations presented in this study, which are reflective of the consensus achieved between coaches of the expert panel. Bold text is used in the tables to note denote statements where ≥70% consensus was achieved; Agreement = agree+strongly agree; Disagreement = disagree+strongly disagree.

Table 2 Responses to statements in the general perceptions of deloading dimension
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Table 3 Responses to statements in the potential applications of deload training dimension
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Table 4 Responses to statements in the designing and implementing deload training dimension
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Table 5 Responses to statements in the creating an inclusive deloading training environment dimension
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General Perceptions of Deloading

In this dimension (Table 2), the expert panel considered deloading to be a reduction in overall training demand facilitated through a decrease in either training volume or intensity of effort. It was agreed that deloading might mitigate the risk of both physical and psychological fatigue, while facilitating recovery and adaptation.

According to the panel, deloading could occur anywhere in the training programme, while the taper would only occur only before a competition. There was consensus that while tapering is designed to achieve peak performance, the purpose of deloading is to promote recovery and preparedness. It was viewed that deloading is not sufficiently represented in strength and conditioning textbooks or qualifications. Moreover, deloading is underrepresented in the available scientific literature, with the current approaches to deloading based primarily on coach experiential knowledge. There was consensus that more scientific research should be conducted to enhance current understanding about deloading, and that research should be made open access to the coaching community. Additionally, it was proposed that networking events, blogs, podcasts and social media-based educational platforms would assist in the dissemination of deloading knowledge.

Potential Applications of Deload Training

In this dimension (Table 3), the panel reached a consensus on the potential benefits of deloading, as well as the methods in which deloading could be integrated into the training programme. It was agreed that deloading could increase adherence to the overall training programme, and reduce the risk of NFOR, OTS, training monotony, and injury, while assisting the athlete in achieving performance peaking.

Designing and Implementing Deload Training

In this dimension (Table 4), the panel agreed that the integration of deloading should be, in part, led by the coach, the athlete, and the available data. There was consensus that the deloading afforded an opportunity to increase training demand in the subsequent training cycle. It was agreed that deloading could be positioned either in the first, middle or final week of a training mesocycle, but that timing of the deload was dependent upon the competition schedule and sporting demands. Deloading could be planned into the athlete’s normal training cycle or utilized when athletes felt physically or mentally fatigued, regardless of where they were within their current mesocycle.

The panel agreed that training volume during deloading could be reduced (relative to the volume utilized in the previous phase of training). This would be achieved through a decrease in either the number of sets per training session, the number of repetitions per set, or through a reduction in training frequency. There was also agreement that a minimum effective dose could be used and that the duration of each training session during deloading could decrease or remain the same. It was agreed that a decrease in session duration would, in part, be the result of a reduction in training volume and intensity.

Panellists agreed that training intensity could either increase or decrease during deloading. There was consensus that, when reduced, training intensity might be lower during the first week of a new mesocycle or could be decreased over consecutive days. Training intensity could also remain the same during the deload, but only when training volume is reduced. It was also agreed that volume and training intensity might decrease during non-competitive periods.

The experts agreed that training volume and intensity were governed, in part, by the demands of the sport, as well as the level of performance or experience, as well as the age of the athlete. There was consensus that the approach to designing and implementing deloading should not be different for male and female athletes.

In relation to exercise selection, exercises might remain unchanged during deloading, or new exercises could be introduced. The rationale for maintaining exercise selection was to reduce the risk of muscle soreness caused by a novel stimulus. There was agreement that main exercises could be adapted by using a lower volume or lower training intensity and that assistance/accessory exercises could be adapted or removed altogether. During the deload, exercise selection should focus on technique for the main exercise(s), the use of multijoint exercises should be maintained and deloading may include activities outside of the gym environment.

It was agreed that deloading could be integrated into the training programme before, during, or at the end of each mesocycle. The consensus was that there could be multiple deloads depending on the length of the mesocycle. How frequent deloading might be integrated would be, in part, dependent on how the athlete responds to the training stimulus presented to them, as well as on other sport training commitments the athlete may have.

Deloading could be pre-planned and organized around the athlete’s lifestyle or integrated using an autoregulatory approach. It was agreed that both the athlete and coach might be involved in scheduling when deloads occurred within the programme.. However, the consensus was that the coach might be more cautious when prescribing deloading to the athlete compared to their own training.

Creating an Inclusive Deloading Training Environment

In this dimension (Table 5), the expert panel agreed that deloading might be easier to implement when the sport has infrequent competitions, and easier to implement when deloading can be integrated around the competitive schedule.

Panellists agreed that barriers to the implementation of deloading could exist. For example, deloading may be difficult to implement due to the athlete’s or coach’s perspective on what a deload is, versus what it actually includes. A lack of athlete or coach education and understanding of deloading could also be a barrier to its integration. Additional barriers that reached consensus were if athletes are highly motivated and “love to train,” the athlete's lifestyle, training culture, or members of the coaching team not working in a collaborative way. To overcome these barriers, it was agreed that coach and athlete education, working in a multi-disciplinary team, and involving athletes in the decision-making process (through active communication) might be beneficial. Moreover, the panel concurred that research-informed practice, athlete autonomy, and the use of consistent terminology might also be advantageous.

Discussion

This study sampled expert opinions from coaches on the integration of deloading into strength and physique sport training programmes. The study systematically gained consensus on factors relating to (1) General Perceptions of Deloading; (2) Potential Applications of Deloading; (3) Designing and Implementing Deloading; and (4), Creating an Inclusive Deloading Training Environment. These findings contribute novel knowledge that will advance the current understanding of deloading in strength and physique sports. Moreover, the results of this study provide the co-creation of new knowledge and understanding between coaches and sports scientists; an important step forward to developing a better understanding of deloading in practice. The results of this study will guide coaches in the integration of deloading in a practical environment and researchers in the development of controlled deloading programmes for scientific research purposes. Additionally, this study also highlights the need for future empirical research in this domain.

The Applications and Objectives of Deloading

A key point of consensus amongst coaches was related to the overall objectives of deloading. Coaches agreed that the purpose of deloading is not to enhance performance per se but to mitigate physiological and psychological fatigue, promote recovery and facilitate physiological adaptation. Moreover, coaches agreed that deloading aims to enhance preparedness for the subsequent training cycle. This rationale is in concordance with the existing (albeit limited) literature [16,17,18, 20,21,22]. Panellists of this study agreed that tapering occurs before a competition, but deloading can occur anywhere in the training programme (i.e., the first, middle, or final week of a training mesocycle). Similar to deloading, the taper is designed to reduce training-induced fatigue while retaining training adaptations [7, 51, 52]. However, the taper only occurs in the final period of training before a major competition and is of paramount importance to an athlete’s competition performance [9, 51]. Consequently, while deloading and tapering share similar structural similarities (i.e., the manipulation of training variables to reduce training-related stress), deloading and tapering are different aspects of training.

Applying consistent terminology to deloading was a key point of agreement between panellists. Currently, no clear definition exists but is critical to propel research in the field. This, in part, might explain the misinterpretation of what is (and is not) deloading, and the often interchangeable use of the terms deloading and tapering [22]. Not only would the development of an operational definition allow for clear differentiation between tapering and deloading, but it would also provide a model by which deloading can be researched for the purpose of scientific inquiry. Therefore, based on expert opinion generated from this study, information synthesized from previous research exploring coaches’ perceptions of deloading, information obtained from relevant previous literature [21, 22] and the authors’ own interpretation, we propose the following definition:

Deloading is a period of reduced training stress designed to mitigate physiological and psychological fatigue, promote recovery, and enhance preparedness for subsequent training.

Coaches agreed that deloading reduces the risk of NFOR, OTS, training monotony and training-related injury. Previous research has elucidated that while short-term periods of highly-demanding resistance exercise training can lead to improvements in both muscular strength and hypertrophy (relative to baseline), chronic periods of training can lead to NFOR and theoretically, the OTS [4, 5]. Indeed, risk factors for the development of NFOR and OTS include undertaking prolonged periods of high-volume and/or high-intensity resistance exercise training without sufficient fuelling or recovery, frequent training to muscular failure/high repeated efforts, and participating in monotonous training with limited variation in training demand or exercise selection [4,5,6, 53]. However, the incidence of NFOR in strength sports and resistance-trained populations is low, even following deliberate attempts to induce maladaptation [4, 5]. Moreover, coaches are not typically concerned that excessive training will result in long-term performance impairment [54]. It is currently unclear whether deloading is a necessary part of the training programme to avoid the deleterious effects of NFOR/OTS.

It has been speculated that prolonged periods of training without sufficient recovery may also contribute to the risk of training-related injury [55]. Further, separating blocks of demanding training with periods of deloading might mitigate the risk of acute joint or musculotendinous injury and subclinical tissue damage [56, 57]. Indeed, it is long-term exposure to training that is assumed to influence injury occurrence, not isolated or single training bouts [55, 58]. However, the relationship between training, performance and injury is complex and multifaceted [59]. Research investigating the impact of training load on the relative risk of injury in strength and physique sports is limited, and most of the available studies in this domain are of low methodological quality [60]. Therefore, while it is plausible to consider that deloading might provide prophylactic benefits to the strength and physique athlete, more research on the epidemiology of injury and changes in risk due to continuous exposure to training needs to be undertaken [61].

Integrating Deloading into the Strength and Physique Athlete’s Training Programme

The panel of coaches agreed that deloading could be integrated into the training programme through alterations in training volume, training intensity or exercise selection. This multifaceted approach to the design of deloading has also been observed in the available literature, where deloads have been implemented through a decrease in repetitions per set or sets per training session [20, 21, 62,63,64,65], a reduction in absolute or relative training intensity [15, 62, 66], or through alterations in exercise selection and configuration [15, 64]. Overall, the variable approach to deloading reported by the expert panel of this research suggests that there is no standardized way to design and integrate deloading into the strength and physique athlete’s training programme. However, there was universal agreement that training volume should be decreased during deloading. Previous literature has shown that undertaking extended periods of high-volume resistance exercise training can result in NFOR [4] and that integrating short-term periods of low training volume can still be effective in maintaining or promoting meaningful increases in muscular strength and hypertrophy, even in resistance-trained individuals and competitive strength athletes [67, 68]. This is perhaps why, in part, coaches involved in this study agreed that a minimum effective dose for volume might be adopted during deloading.

Coaches agreed that while deloading might be positioned in the final week of the mesocycle, it can also be placed in the first week of a new mesocycle. Typically, a new mesocycle of training will incorporate new exercises [8] emphasizing skill and technique development and approaching training in a way that focuses on quality rather than quantity [69]. Previous research [22] has highlighted that deloading presents an opportunity for the athlete to develop new techniques and the incorporation of novel exercises, therefore, there is a rationale for the deloading to occur in the first week of a new mesocycle. Consequently, deloading might incorporate some degree of novelty as a method to reduce training monotony and develop new skills in preparation for the subsequent mesocycle. However, caution should be taken when adjusting exercise selection due to a potential increase in muscle soreness caused by unaccustomed resistance exercise training [70]. Therefore, incorporating new exercises into the deload, with concomitant reductions in training volumes and/or relative intensities, could allow for the integration of novel exercise selection while mitigating the risk of training-related muscle soreness.

Training programmes aiming to enhance muscular strength or hypertrophy have traditionally adopted a periodized approach, where training is organized into a series of training cycles separated by phases of reduced training stress [2, 16, 18, 71]. Strength and physique training programmes are traditionally modeled on a predicted pattern of response to training stress, i.e., the stimulus-fatigue-recovery-adaptation model [17, 72]. Indeed, it is common within strength and physique sports training programmes to adopt a pre-planned approach whereby training is gradually progressed each week of the mesocycle until a deload is applied in the final week [20, 64]. In this sense, regular (every 4–8 weeks) pre-planned deloading serves a precautionary purpose and is likely based on the assumption that phases of reduced training stress are required to allow physiological adaptation to occur [3, 17]. However, while there is evidence to suggest that systematic variation of training can lead to improvements in select measures of athletic performance [16, 18], there is limited evidence to suggest that pre-planned, periodized training is superior to non-periodized training [72,73,74]. Consequently, regular pre-planned periods of reduced training stress might not be necessary, and this is perhaps the reason why some strength and physique coaches choose not to pre-plan a deload or do not consider it necessary to prescribe them rigidly [22]. It is also worth noting that periodization of resistance exercise training volume and intensity does not seemingly lead to greater muscular hypertrophy compared to non-periodized training [75, 76]. Moreover, none of the studies included in reviews exploring the effects of periodized training on muscular hypertrophy have been designed to directly enhance hypertrophy as the principal outcome [75, 76]. Only strength training protocols have been meta-analyzed for their impact on hypertrophy. Therefore, it is currently unclear whether competitive physique athletes intending to develop muscular hypertrophy for aesthetic reasons should periodize their training [77].

There are very few empirical studies that have investigated the effects of continuous training (training without deloading) versus periodic training (training blocks that are separated by deloading) [78, 79]. In studies by Ogasawara et al. [78, 79], no statistically significant differences were observed in measures of muscular strength or hypertrophy between a continuous training group and a group integrating a three-week period of training cessation after six weeks of training over either a 15 or 24-week period. Additionally, previous research has speculated that prolonged training without sufficient recovery might lead to a blunting of the anabolic signalling process that underpins the adaptive response to resistance exercise training, and as such, integrating short-term periods of deloading might “resensitize” the hypertrophic response to training [80]. However, the influence of deloading on a possible desensitization/resensitization effect have not been studied and it is currently unknown if deloading enhances the adaptive response to training.

Autoregulation is an emergent method used within resistance exercise training prescription to adjust the training volume and intensity of each session based on individual daily fluctuations in fitness, fatigue, and preparedness [81, 82]. An autoregulated approach avoids adopting pre-planned phases of training, and instead, favours continuous modification of training in response to the athlete’s individual rate of adaptation [83]. In resistance exercise training programmes that emphasize muscular strength or hypertrophy, autoregulation can be applied through alterations in either objective or subjective within-session measures (e.g., ratings of perceived exertion, reps in reserve, velocity-based training) or between-session measures (e.g., countermovement jump, 1-RM) [83, 84]. Therefore, adopting an autoregulated approach allows the strength and physique coach to prescribe heavier or lighter training in an undulating manner, rather than in a rigid or pre-planned way [85]. Previous studies have demonstrated that autoregulation of training variables can lead to improvements in both muscular strength and hypertrophy while also deterring maladaptation [81, 86]. While evidence suggests that utilizing an autoregulated deloading might negate (or at least reduce the necessity) of pre-planned deloads, further research is required to accurately assess its effects on muscular strength and hypertrophy in the subsequent training phase compared to a pre-planned paradigm. Panellists agreed that the integration of deloading into the training programme should be, in part, led by the coach, the athlete, and the individual athlete’s performance data. This is perhaps reflected in the agreement to use an autoregulation approach to deloading as it allows a flexible approach to training where the coach and athletes select the type or difficulty of the training session based on perceived capability to perform (i.e., high fatigue levels or high readiness to train) [82]. In this sense, the coach and athlete can use the available data to triangulate the day’s training.

Overall, deloading should be approached in an individualized, athlete-centred manner, combining practice-based guidelines with experience and tacit knowledge. The athlete’s level of competition, training history, chronological and training age, the importance of competition, and lifestyle factors (e.g., work or family commitments), as well as the demands of the sport and competition schedule, should all be considered when developing deloading training [22]. Coaches should adopt a research-informed approach when integrating deloading into the training programme. Therefore, the strength and physique coach must undertake a thorough needs analysis of the athlete and their sport prior to integrating deloading, using an appropriate framework of practice to properly address the factors that influence the response to training [87].

Figure 2 provides a resource designed to assist coaches in the integration of deloading into strength and physique training programmes. This resource was developed using statements that reached consensus in Round 3 and was reviewed by all authors to ensure the accuracy of information but also to remain as faithful as possible to the original wording of statements reaching consensus. It is recommended that before integrating deloading into strength and physique training programmes, coaches engage with this resource and relevant coach education material.

Fig. 2
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Principles framework for integrating deloading into strength and physique training programmes

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Developing a Collaborative Understanding of Deloading

The value of experiential knowledge for informing strength and conditioning practice has been largely neglected due to difficulties in acquiring data via classic experimental designs. As a result, the rationale for evidence-based knowledge in strength and conditioning has been skewed in the way of limiting the categorization of knowledge to influence practice into ‘what’ in the absence of ‘why’ and ‘how’ [24, 88]. The panel of coaches in this study agreed that deloading research is underrepresented in both published peer-reviewed literature and professional resources (i.e., strength and conditioning textbooks and qualifications). Further, that non-traditional media, such as blogs, podcasts and YouTube videos could be used to disseminate knowledge of deloading.

Advances in theoretical sports science knowledge, and rapid changes in technology to support athlete development, means there is a need for strength and physique coaches to stay up to date with emerging knowledge [89]. Coaches frequently learn from informal sources such as conferences and podcasts as they tend to be contextually relevant, accessible, and applicable to the practical environment [90, 91]. Indeed, while peer-reviewed, published sports science research is used to inform and update practice, coaches are less likely to gain new information directly from scientific sources due to a lack of access (something agreed upon by the expert panel) and a lack of time [90]. This might be, in part, why coaches involved in this research consider current approaches to deloading to be primarily based on coach experiential knowledge of deloading.

Research from Shaw and McNamara [92] has demonstrated that open-access podcasts provide an alternative source of information for coaches and sports scientists due to their convenience, accessibility, and authenticity. As a novel medium of knowledge transfer, educational podcasts provide profession-specific knowledge to increase understanding relating to a specific topic [93]. Moreover, podcast creators often use scientific literature to research for a specific podcast episode [94], therefore the importance of peer-reviewed research cannot be dismissed. However, while podcasts are the preferred vehicle for knowledge transfer in the strength and physique coaching community, it is difficult to verify the legitimacy and accuracy of the information distributed in some podcasts [94].

Coaches agreed that the current understanding of deloading is governed primarily by experiential knowledge. Given that the coach–sports scientist relationship can contribute to establishing optimal practices in high-performance sporting environments and enhance the transfer of knowledge [95], coaches’ knowledge should serve as a starting point for the development of deloading protocols used for the design and dissemination of scientific findings. The integration of coach experiential knowledge (i.e., knowledge gained by ‘doing’ [96]), and empirical knowledge on deloading is displayed in Fig. 3, with the overlap of the two bodies of knowledge being the result of collaboration between coaches and sports scientists in a ‘department of methodology’ [24]. Over time, it is anticipated that this overlap may lead to the enhancement of experimental research within applied environments and assist in the development of robust deloading practices through collaborative design, shared principles and unified language [24].

Fig. 3
figure 3

A theoretical framework for enhancing deloading knowledge using a department of methodology approach. (Adapted from Rothwell et al. [24])

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While this study assists in developing an understanding of the integration of deloading into strength and physique sports, we acknowledge some potential limitations of this study. The Delphi approach has previously been criticized for its potential for issues in achieving expert selection, researcher bias, and restrictive communication methods [97]. Adopting a pragmatic approach to the Delphi process, the authors acknowledged potential limitations during decision-making, with the best attempts made to uphold rigour in the planning and delivery of the Delphi study. The authors consulted peer-reviewed research when making decisions, for example when deciding the inclusion and exclusion of selected ‘experts', the number of rounds, the analytical approach and thresholds for consensus before the study commenced [33]. Aligned with a pragmatic approach, a ‘don't know’ option was provided to ensure that participants had an opportunity to report if they did not have an opinion/attitude on a particular statement, rather than feel obliged to provide an answer. The authors acknowledge that while this is an acceptable approach [48], the language used for the ‘don’t know’ response has been debated in the literature.

A possible limitation concerns the development of the framework for integrating deloading into strength and physique sports training programmes (Fig. 2) which has been developed to act as guidance for coaches and sports scientists on the design and implementation of deloading training. While the information located in this framework remained as faithful as possible to the statements presented to the participants, it would be practically meaningful if a fourth round had been included, where participants could provide feedback on the framework to assess its accuracy and usability. Doing so might enhance the clarity of presentation, application and understanding of the framework in practice. Therefore, we recommend that future research should seek coaches’ opinions on the framework presented in Fig. 2 and make necessary revisions to its structure and presentation as required.

Conclusion

This study acquired expert opinion on the integration of deloading in strength and physique sports. Informed by the findings from the study, consensus was acquired for the development of design principles relating to (1) General Perceptions of Deloading; (2) Potential Applications of Deloading; (3) Designing and Implementing Deloading; and (4), Creating an Inclusive Deloading Training Environment. The novel design principles outlined in this study provide a theoretical and coach-informed method for integrating deloading into strength and physique sports training programmes. In this study, we also propose a new definition of deloading.

Despite the expansion of scientific knowledge exploring deloading, more in-depth research is required. While the framework developed in this research enhances the current understanding of deloading, assisting both strength and physique coaches and sports scientists in the design and implementation of deloading training, it is our recommendation that scientists continue to collaborate with coaches and continue to consolidate deloading knowledge.