The effects of collagen peptides on muscle damage, inflammation and bone turnover following exercise: a randomized, controlled trial

This study examined whether consuming collagen peptides (CP) before and after strenuous exercise alters markers of muscle damage, inflammation and bone turnover. Using a double-blind, independent group’s design, 24 recreationally active males consumed either 20 g day−1 of CP or a placebo control (CON) for 7 days before and 2 days after performing 150 drop jumps. Maximal isometric voluntary contractions, countermovement jumps (CMJ), muscle soreness (200 mm visual analogue scale), pressure pain threshold, Brief Assessment of Mood Adapted (BAM +) and a range of blood markers associated with muscle damage, inflammation and bone turnover C-terminal telopeptide of type 1 collagen (β-CTX) and N-terminal propeptides of type 1 pro-collagen (P1NP) were measured before supplementation (baseline; BL), pre, post, 1.5, 24 and 48 h post-exercise. Muscle soreness was not significantly different in CP and CON (P = 0.071) but a large effect size was evident at 48 h post-exercise, indicative of lower soreness in the CP group (90.42 ± 45.33 mm vs. CON 125.67 ± 36.50 mm; ES = 2.64). CMJ height recovered quicker with CP than CON at 48 h (P = 0.050; CP 89.96 ± 12.85 vs. CON 78.67 ± 14.41% of baseline values; ES = 0.55). There were no statistically significant effects for the other dependent variables (P > 0.05). β-CTX and P1NP were unaffected by CP supplementation (P > 0.05). In conclusion, CP had moderate benefits for the recovery of CMJ and muscle soreness but had no influence on inflammation and bone collagen synthesis.


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Direct damage to the ECM has also been observed histologically, in which the ECM is seen to 89 be detached from the myo fibre with immunochemical staining (Stauber et al. 1990). Indirect function. This assertion is supported by a recent animal study that found that mice with a 96 genetic mutation encoding for collagen type V1, which is important in the formation of the 97 basement membrane of the ECM, generate significantly less muscle force than their healthy 98 counterparts (Zou et al., 2011). This raises the possibility that attenuating damage to the ECM 99 and/or attempting to accelerate the remodeling process might be of benefit for recovery of 100 muscle function after strenuous physical exercise. 101 While most interventions attempting to accelerate ECM remodeling are pharmacological 102 (Mackey & Kjaer, 2014) there is a growing interest in the effects of supplements containing 103 collagen specific peptides, or gelatin (partially hydrolyzed collagen), on collagen synthesis 104 (Shaw et al. 2016). These supplements are derived from the connective tissue of animals and 105 contain high amounts of the collagen specific amino acids (AA) hydroxyproline, glycine and 106 proline that together comprise almost 2/3 rds of the total AA in collagen (Li & Wu, 2018). Upon

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Although in vivo studies are still scarce, Shaw et al. (2016) also showed that ingestion of 5 or 112 15 mg of gelatin augmented bone collagen synthesis following acute mechanical loading (jump 113 rope), as evidenced by increase in the bone formation marker pro-collagen type 1 amino-114 terminal propeptide (P1NP). This led the authors to speculate that these collagen specific 115 peptides could serve as a useful supplement to aid connective tissue repair after exercise and/or 116 injury.

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If these AA can stimulate collagen synthesis, it would be reasonable to assume that increasing 119 their availability after exercise might be able to modify ECM dysfunction -either by 120 attenuating damage or enhancing the remodeling process -and that this might, in turn, 121 accelerate acute functional recovery following strenuous exercise. In support, there is now a 122 growing body of evidence to suggest collagen hydrolysate supplementation could attenuate has also reported that CP attenuated creatine kinase (CK) activity following muscle-damaging 129 exercise, indicative of enhanced muscle recovery (Lopez et al. 2015). Collectively, the 130 aforementioned findings suggest that CP hold promise as a recovery aid following strenuous 131 exercise and that they warrant further exploration.

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Consequently, the aim of this study was to examine whether consuming CP before and after a 134 bout of strenuous exercise could attenuate indirect markers of muscle damage and recovery.

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Our primary outcome measures were functional in nature; muscle soreness and muscle 136 function, given they are widely accepted to be the most valid and reliable markers of EIMD 137 and recovery (Warren et al. 1999) and have the most practical relevance to active populations. Twenty-four males, who were recreationally active (defined as exercising ~2 d·wk· -1 ) but 145 unaccustomed to high force plyometric exercise, volunteered for this study (see Table 1 for 146 physical characteristics). Prior to study entry, participants completed a medical screening 147 questionnaire and were excluded if they had a known food allergy, currently, or had recently  In a double blind, placebo-controlled, independent groups design, participants were 156 randomized to 1 of 2 experimental groups; a treatment group, which received 20 g·d -1 of CP, 157 and a control group, which received an isoenergetic and isovolumic placebo CON). Baseline  The baseline CMJ scores were used to randomly match the participants in each group.

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Following this visit, participants consumed their assigned supplements (CP or CON) for 7 days 163 before muscle-damaging exercise. Supplements were consumed twice per day; one serving (10 164 g) in the morning with breakfast, and another with their evening meal. On the 8 th day, before   The CP supplement was provided by Rousselot BVBA (Ghent, Belgium) and is commercially 222 available as Peptan ® . Each serving contained 10 g of hydrolyzed collagen peptides derived 223 from bovine hide. Each serving of the CON contained 10 g of pure maltodextrin with no AA; 224 this was also supplied by Rousselot BVBA. Both supplements were packaged as powder in 225 identical 10 g sachets. As in a previous study (Shaw et al., 2016), they were consumed with 226 water and 50 ml of Ribena Light (Suntory, China), which is rich in vitamin C (80 mg per 227 serving) and therefore thought to enhance collagen synthesis.

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Because of the paucity of studies on CP and EIMD, selecting the most appropriate dose and 229 protocol was a challenge. The rationale for our eventual selection was based on evidence from 230 several lines of enquiry: those examining nutritional supplements on EIMD; those examining 231 collagen pharmacokinetics, and; those examining collagen synthesis. Foremost, the timings. 232 We opted to provide the supplements twice daily for 7 days before exercise because studies 233 with fruit juices and branched chain AA showed that such a protocol, typically known as a pre-   (ES) and confidence intervals, enabling us to get an idea of how meaningful any observed 296 changes were. In addition, as this was a proof of principle study, that is, it is the first study to 297 assess the effects of the intervention on these specific outcomes, we felt this statistical approach 298 would allow us to better detect subtle differences that can be missed when solely relying on 299 null hypothesis significance testing (NHST) (due to low sample size, high inter-individual

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Participant's physical characteristics, baseline scores for each variable, and average 322 macronutrient intake throughout the testing period are presented in Table 1. There were no 323 group difference in any of these variables (P > 0.05); with MBI analysis, effects were all   78.44 ± 17.7% in CON, indicating a likely benefit of CP with MBI analysis (Table 2); however, 353 the ES was small (0.51). 355 BAM+ scores were reduced in both CP and CON (time effect; P = 0.001) but no time*group 356 or group interactions were observed (P > 0.05; Figure 1). With MBI analysis, effects were 357 unclear or trivial at all-time points and ES were small (≤0.24); Table 2 Table 3). There were no time, group or interaction effects for IL-6 (P > 0.05); however, The main finding of this study is that CP supplementation accelerated the recovery of CMJ 413 performance and tended to reduce muscle soreness following a bout of muscle-damaging 414 exercise. The CP supplement had little to no influence on serum protein release, β-NGF, IL-6, 415 and bone turnover markers post-exercise, but there were possibly some small increases in 416 leukocyte numbers with CP supplementation post-exercise. This is the first study to suggest 417 that CP could modulate the recovery process following eccentrically biased exercise.

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Although not statistically significant, (P = 0.071), the large effect sizes suggest that those in 419 the CP group reported less muscle soreness at 24 and 48 h post-exercise. Based on the 90% CI, 420 the true impact of CP on muscle soreness was a 4.1-54.4 mm reduction on the VAS scale, 421 which is arguably a meaningful decrease in athletic populations. This reduction in soreness, 422 however, was only evident from the subjective assessment with the VAS, as no group 423 differences were detected in PPT. We are unsure of the precise reason for this discrepancy, but

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There were no statistically significant changes in serum proteins ALT, AST, LDH and CK.

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Possibly and likely beneficial reductions were observed in ALT, AST and CK following CP 485 ingestion with MBI analysis; however, these effects were small to moderate. These findings 486 are in contrast to recent study that reported significant reductions in plasma CK and LDH in 487 the 24-72 h following muscle-damaging exercise with 3 g of CP ingestion (Lopez et al., 2015). 488 The discrepancy in findings between our study and that of Lopez et al. (2015) could be due to 489 the much higher inter-individual variability for these markers in our study. Indeed, the 490 heterogenic responses could be why we were unable to detect subtle differences between group

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ELISA) could provide at least a partial explanation. Regardless, our data do not support the 514 idea that acute CP ingestion stimulates bone collagen synthesis after strenuous physical 515 exercise. It is likely that a longer supplementation period is required for these effects to 516 manifest; indeed, a recently published study found that 12 months of daily CP ingestion (5 g) 517 increased P1NP and decreased β-CTX in post-menopausal women (König et al. 2018). Future 518 studies should assess the effects of longer supplementation periods on bone turnover in 519 physically active individuals.

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The main limitation of this study is that due to ethical constraints, we were unable to take 521 muscle biopsy samples in this study, instead having to rely on indirect markers of muscle 522 damage and inflammation to evaluate the effects of CP. We do not perceive this to be a 523 limitation in terms of assessing function and subjective wellbeing as muscle soreness and 524 muscle function are still the most valid and reliable measures of EIMD with the most practical 525 relevance (Warren et al. 1999). However, the changes we observed at the systemic level might 526 not reflect the changes at the local level, and thus, we must emphasise caution when interpreting 527 these findings. Moreover, that there is no evidence to date that CP influences connective tissue 528 synthesis in vivo, we are unable to provide any concrete evidence as to the possible mechanisms 529 involved, but hope this research stimulates further studies in this area.

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In conclusion, this study showed that 9 days of CP supplementation might help to accelerate 531 the recovery of muscle function and attenuate muscle soreness following strenuous physical 532 exercise. The underlying mechanisms remain unclear, but we speculate that they are related to 533 an increase in collagen synthesis in the connective tissues surrounding the muscle and/or 534 modulation of the inflammatory response to the exercise bout, which could accelerate the early 535 remodelling process. In addition to testing this hypothesis, future studies are needed to evaluate 536 the optimal dose and whether such effects are present in elite athletic populations.