Advertisement

European Journal of Applied Physiology

, Volume 112, Issue 11, pp 3865–3879 | Cite as

Variation of force amplitude and its effects on local fatigue

  • Marcus YungEmail author
  • Svend Erik Mathiassen
  • Richard P. Wells
Original Article

Abstract

Trends in industry are leaning toward stereotyped jobs with low workloads. Physical variation is an intervention to reduce fatigue and potentially musculoskeletal disorders in such jobs. Controlled laboratory studies have provided some insight into the effectiveness of physical variation, but very few have been devoted to force variation without muscular rest as a component. This study was undertaken to determine multiple physiological responses to five isometric elbow extension protocols with the same mean amplitude (15 % maximum voluntary contraction, MVC), cycle time (6 s), and duty cycle (50 %). Sustained (15 %Sus) and intermittent contractions including zero force (0–30 %Int) differed significantly in 19 of 27 response variables. Contractions varying by half the mean force (7.5–22.5 %Int) led to 8 and 7 measured responses that were significantly different from 0–30 %Int and 15 %Sus, respectively. A sinusoidal condition (0–30 %Sine) resulted in 2 variables that were significantly different from 0–30 %Int, and 16 different from 15 %Sus. Finally, ten response variables suggested that varying forces with 1 % as the lower contraction level was significantly less fatiguing than 15 %Sus, while no responses were significantly different from 0–30 %Int. Sustained contractions led to decreased twitch force 24-h post-exercise, whereas recovery was complete within 60 min after intermittent contractions. This suggests that time-varying force may be a useful intervention to reduce local fatigue in workers performing low-load tasks, and also that rest per se did not seem to cause any extraordinary effects beyond those predictable from the force variation amplitude.

Keywords

Physical variation Intermittent exercise Work breaks Recovery Ergonomics 

Notes

Acknowledgments

The authors wish to thank Dr. A.R. Tupling for his advice and help with this project. This project was funded by a research grant provided by the Workplace Safety and Insurance Board (Ontario).

References

  1. El Ahrache K, Imbeau D, Farbos B (2006) Percentile values for determining maximum endurance times for static muscular work. Int J Ind Ergonomics 36:99–108. doi: 10.1016/j.ergon.2005.08.003 CrossRefGoogle Scholar
  2. Allison GT, Fujiwara T (2002) The relationship between EMG median frequency and low frequency band amplitude changes at different levels of muscle capacity. Clin Biomech 17:464–469CrossRefGoogle Scholar
  3. Al-Zahrani E, Gunasekaran C, Callaghan M, Gaydecki P, Benitez D, Oldham J (2009) Within-day and between-days reliability of quadriceps isometric muscle fatigue using mechanomyography on healthy subjects. J Electromyogr Kinesiol 19:695–703. doi: 10.1060/j.jelekin.2007.12.007 PubMedCrossRefGoogle Scholar
  4. Arvidsson I, Hansson G-Å, Mathiassen SE, Skerfving S (2006) Changes in physical workload with implementation of mouse-based information technology in air traffic control. Int J Ind Ergonomics 36:613–622. doi: 10.1016/j.ergon.2006.03.002 CrossRefGoogle Scholar
  5. Baker AJ, Kostov KG, Miller RG, Weiner MW (1993) Slow force recovery after long-duration exercise: metabolic and activation factors in muscle fatigue. J Appl Physiol 74:2294–2300PubMedCrossRefGoogle Scholar
  6. Bigland-Ritchie B, Donovan EF, Roussos CS (1981) Conduction velocity and EMG power spectrum changes in fatigue of sustained maximal efforts. J Appl Physiol 51:1300–1305PubMedGoogle Scholar
  7. Bilodeau M (2006) Central fatigue in continuous and intermittent contractions of triceps brachii. Muscle Nerve 34:205–213. doi: 10.1002/mus.20572 PubMedCrossRefGoogle Scholar
  8. Bilodeau M, Arsenault AB, Gravel D, Bourbonnais D (1991) EMG power spectra of elbow extensors during ramp and step isometric contractions. Eur J Appl Physiol 63:24–28. doi: 10.1007/BF00760796 CrossRefGoogle Scholar
  9. Björkstén M, Jonsson B (1977) Endurance limit of force in long-term intermittent static contractions. Scand J Work Environ Health 3:23–27PubMedCrossRefGoogle Scholar
  10. Blangsted AK, Søgaard K, Christensen H, Sjøgaard G (2004) The effect of physical and psychosocial loads on the trapezius muscle activity during computer keying tasks and rest periods. Eur J Appl Physiol 91:253–258. doi: 10.1007/s00421-003-0979-z PubMedCrossRefGoogle Scholar
  11. Blangsted AK, Sjøgaard G, Madeleine P, Olsen HB, Søgaard K (2005) Voluntary low-force contraction elicits prolonged low-frequency fatigue and changes in surface electromyography and mechanomyography. J Electromyogr Kinesiol 15:138–148. doi: 10.1016/j.jelekin.2004.10.004 PubMedCrossRefGoogle Scholar
  12. Brewer S, Van Eerd D, Amick BC, Irvin E, Daum KM, Gerr F, Moore JS, Cullen K, Rempel D (2006) Workplace interventions to prevent musculoskeletal and visual symptoms and disorders among computer users: a systematic review. J Occup Rehabil 16:325–358. doi: 10.1007/s10926-006-9031-6 PubMedCrossRefGoogle Scholar
  13. Büdingen HJ, Freund HJ (1976) The relationship between the rate of rise of isometric tension and motor unit recruitment in a human forearm muscle. Pflug Arch 362:61–67CrossRefGoogle Scholar
  14. Byström SEG, Fransson-Hall C (1994) Acceptability of intermittent handgrip contractions based on physiological response. Hum Factors 36:158–171PubMedGoogle Scholar
  15. Byström SEG, Kilbom A (1990) Physiological response in the forearm during and after isometric intermittent handgrip. Eur J Appl Physiol 60:457–466. doi: 10.1007/BF00705037 CrossRefGoogle Scholar
  16. Byström SEG, Mathiassen SE, Fransson-Hall C (1991) Physiological effects of micropauses in isometric handgrip exercise. Eur J Appl Physiol 63:405–411CrossRefGoogle Scholar
  17. Commissaris DACM, Douwes M, Schoenmaker N, de Korte EM (2006) Recommendations for sufficient physical activity at work. In: Proceedings of the IEA 2006 conference, MaastrichtGoogle Scholar
  18. Dahmane R, Valencic V, Knez N, Erzen I (2000) Evaluation of the ability to make non-invasive estimation of muscle contractile properties on the basis of the muscle belly response. Med Biol Eng Comput 39:51–55. doi: 10.1007/BF02345266 CrossRefGoogle Scholar
  19. de Looze M, Bosch T, van Dieen JH (2009) Manifestations of shoulder fatigue in prolonged activities involving low-force contractions. Ergonomics 52:428–437. doi: 10.1080/00140130802707709 PubMedCrossRefGoogle Scholar
  20. Ebersole KT, O’Connor KM, Weir AP (2006) Mechanomyographic and electromyographic responses to repeated concentric muscle actions of the quadriceps femoris. J Electromyogr Kinesiol 16:149–157. doi: 10.1016/j.jelekin.2005.05.005 PubMedCrossRefGoogle Scholar
  21. Edwards RHT, Hill DK, Jones DA, Merton PA (1977) Fatigue of long duration in human skeletal muscle after exercise. J Physiol 272:769–778PubMedGoogle Scholar
  22. Enoka RM (1995) Mechanisms of muscle fatigue: central factors and task dependency. J Electromyogr Kinesiol 5:141–149. doi: 10.1016/1050-6411(95)00010-W PubMedCrossRefGoogle Scholar
  23. Falla D, Farina D (2007) Periodic increases in force during sustained contraction reduce fatigue and facilitate spatial redistribution of trapezius muscle activity. Exp Brain Res 182:99–107. doi: 10.1007/s00221-007-0974-4 PubMedCrossRefGoogle Scholar
  24. Fernström EAC, Åborg CM (1999) Alterations in shoulder muscle activity due to changes in data entry organisation. Int J Ind Ergonomics 23:231–240. doi: 10.1016/s0169-8141(97)00058-9 CrossRefGoogle Scholar
  25. Forsman M, Kadefors R, Zhang Q, Birch L, Palmerud G (1999) Motor-unit recruitment in the trapezius muscle during arm movements and in VDU precision work. Int J Ind Ergonomics 24:619–630. doi: 10.1016/s0169-8141(98)00067-5 CrossRefGoogle Scholar
  26. Frazer M, Norman R, Wells RP, Neumann P (2003) The effects of job rotation on the risk of reporting low back pain. Ergonomics 46:904–919. doi: 10.1080/001401303000090161 PubMedCrossRefGoogle Scholar
  27. Frey Law LA, Avin KG (2010) Endurance time is joint-specific: a modelling and meta-analysis investigation. Ergonomics 53:109–129. doi: 10.1080/00140130903389068 PubMedCrossRefGoogle Scholar
  28. Gjovaag TF, Dahl HA (2008) Effect of training with different intensities and volumes on muscle fibre enzyme activity and cross sectional area in the m. triceps brachii. Eur J Appl Physiol 103:399–409. doi: 10.1007/s00421-008-0725-7 PubMedCrossRefGoogle Scholar
  29. Griffin L, Garland SJ, Ivanova T, Hughson RL (2001) Blood flow in the triceps brachii muscle in humans during sustained submaximal isometric contractions. Eur J Appl Physiol 84:432–437. doi: 10.1007/s004210100397 PubMedCrossRefGoogle Scholar
  30. Hagberg M (1981) Muscular endurance and surface electromyogram in isometric and dynamic exercise. J Appl Physiol 51:1–7PubMedGoogle Scholar
  31. Hägg GM (1991) Static work loads and occupational myalgia—a new explanation model. In: Anderson PA, Hobart DJ, Dainoff JV (eds) Electromyographical kinesiology. Elsevier, Amsterdam, pp 141–144Google Scholar
  32. Hägg GM (1992) Interpretation of EMG spectral alterations indexes at sustained contraction. J Appl Physiol 73:1211–1217PubMedGoogle Scholar
  33. Hunter SK, Lepers R, MacGillis CJ, Enoka RM (2003) Activation among elbow flexor muscles differ when maintaining arm position during a fatiguing contraction. J Appl Physiol 94:2439–2447. doi: 10.1152/japplphysiol.01038.2002 PubMedGoogle Scholar
  34. Iridiastadi H, Nussbaum MA (2006) Muscle fatigue and endurance during repetitive intermittent static efforts: development of prediction models. Ergonomics 49:344–360. doi: 10.1080/00140130500475666 PubMedCrossRefGoogle Scholar
  35. Iridiastadi H, Nussbaum MA, van Dieën JH (2008) Muscular load characterization during isometric shoulder abductions with varying force. J Electromyogr Kinesiol 8:695–703. doi: 10.1016/j.jelekin.2007.01.011 CrossRefGoogle Scholar
  36. Jørgensen K, Fallentin N, Krogh-Lund C, Jensen B (1988) Electromyography and fatigue during prolonged, low-level static contractions. Eur J Appl Physiol 57:316–321. doi: 10.1007/BF00635990 CrossRefGoogle Scholar
  37. Kent-Braun JA, Ng AV, Doyle JW, Towse TF (2002) Human skeletal muscle responses vary with age and gender during fatigue due to incremental isometric exercise. J Appl Physiol 93:1813–1823. doi: 10.1152/japplphysiol.00091.2002 PubMedGoogle Scholar
  38. Konz S (1998) Work/rest: part II—the scientific basis (knowledge base) for the guide. Int J Ind Ergonomics 22:73–99CrossRefGoogle Scholar
  39. Kossev A, Christova P (1998) Discharge pattern of human motor units during dynamic concentric and eccentric contractions. Electroencephalogr Clin Neurophysiol 109:245–255PubMedCrossRefGoogle Scholar
  40. Krogh-Lund C, Jørgensen K (1992) Modification of myo-electric power spectrum in fatigue from 15% maximum voluntary contraction of human flexor muscles, to limit of endurance: reflection of conduction velocity variation and/or centrally mediated mechanisms? Eur J Appl Physiol 64:359–370. doi: 10.1007/BF00636225 CrossRefGoogle Scholar
  41. Kuijer PPFM, de Vries WHK, van der Beek AJ, van Dieen JH, Frings-Dresen MHW (2004) Effect of job rotation on work demands, workload, and recovery of refuse truck drivers and collectors. Hum Factors 46:437–448. doi: 10.1518/hfes.46.3.437.50403 PubMedCrossRefGoogle Scholar
  42. Lindman R, Eriksson A, Thornell LE (1991) Fiber type composition of the human female trapezius muscle: enzyme-histochemical characteristics. Am J Anat 190:385–392. doi: 10.1002/aja.1001900406 PubMedCrossRefGoogle Scholar
  43. Ljung BO, Lieber RL, Fridén L (1999) Wrist extensor muscle pathology in lateral epicondylitis. J Hand Surg 24:177–183. doi: 10.1054/JHSB.1998.0178 Google Scholar
  44. Madeleine P, Jørgensen LV, Søgaard K, Arendt-Nielsen L, Sjøgaard G (2002) Development of muscle fatigue as assessed by electromyography and mechanomyography during continuous and intermittent low-force contractions: effects of the feedback mode. Eur J Appl Physiol 87:28–37. doi: 10.1007/s00421-002-0578-4 PubMedCrossRefGoogle Scholar
  45. Mathiassen SE (1993) The influence of exercise/rest schedule on the physiological and psychophysical response to isometrics shoulder–neck exercise. Eur J Appl Physiol 67:528–539. doi: 10.1007/BF00241650 CrossRefGoogle Scholar
  46. Mathiassen SE (2006) Diversity and variation in biomechanical exposure: what is it, and why would we like to know? Appl Ergonomics 37:419–427. doi: 10.1016/j.apergo.2006.04.006 CrossRefGoogle Scholar
  47. Mathiassen SE, Åhsberg E (1999) Prediction of shoulder flexion endurance from personal factors. Int J Ind Ergonomics 24:315–329. doi: 10.1016/S0169-8141(98)00039-0 CrossRefGoogle Scholar
  48. Mathiassen SE, Turpin-Legendre E (1998) Reduction of shoulder elevation fatigue by periods of increased load. In: Proceedings of the 3rd international scientific conference on prevention of work-related musculoskeletal disorders (PREMUS). Finnish Institute of Occupational Health, HelsinkiGoogle Scholar
  49. Mathiassen SE, Winkel J (1992) Can occupational guidelines for work–rest schedules be based on endurance time data? Ergonomics 35:253–259. doi: 10.1080/00140139208967811 PubMedCrossRefGoogle Scholar
  50. Mathiassen SE, Burdorf A, van der Beek AJ, Hansson G-Å (2003) Efficient one-day sampling of mechanical job exposure data—a study based on upper trapezius activity in cleaners and office workers. Am Ind Hyg Assoc J 64:196–211. doi: 10.1080/15428110308984809 CrossRefGoogle Scholar
  51. Mital A, Bishu RR, Manjunath SG (1991) Review and evaluation of techniques for determining fatigue allowances. Int J Ind Ergonomics 8:165–178. doi: 10.1016/0169-8141(91)90017-G CrossRefGoogle Scholar
  52. Möller T, Mathiassen SE, Franzon H, Kihlberg S (2004) Job enlargement and mechanical exposure variability in cyclic assembly work. Ergonomics 47:19–40. doi: 10.1080/0014013032000121651 PubMedCrossRefGoogle Scholar
  53. Moore AE, Wells RP (2005) Effect of cycle time and duty cycle on psychophysically determined acceptable levels in a highly repetitive task. Ergonomics 48:859–873. doi: 10.1080/00140130512331332909 PubMedCrossRefGoogle Scholar
  54. Moxham J, Edwards RHT, Aubier M, De Troyer A, Farkas G, Macklem PT, Roussos C (1982) Changes in EMG power spectrum (high-to-low ratio) with force fatigue in humans. J Appl Physiol 53:1094–1099PubMedGoogle Scholar
  55. Nordander C, Hansson GA, Rylander L, Asterland P, Byström JU, Ohlsson K, Balogh I, Skerfving S (2000) Muscular rest and gap frequency as EMG measures of physical exposure: the impact of work tasks and individual related factors. Ergonomics 43:1904–1919. doi: 10.1080/00140130050174536 PubMedCrossRefGoogle Scholar
  56. Nussbaum MA, Clark LL, Lanza MA, Rice KM (2001) Fatigue and endurance limits during intermittent overhead work. Am Ind Hyg Assoc J 62:446–456CrossRefGoogle Scholar
  57. O’Sullivan LW, Gallwey TJ (2005) Forearm torque strengths and discomfort profiles in pronation and supination. Ergonomics 48:703–721. doi: 10.1080/00140130500070954 PubMedCrossRefGoogle Scholar
  58. Perry SR, Housh TJ, Weir JP, Johnson GO, Bull AJ, Ebersole KT (2001) Mean power frequency and amplitude of the mechanomyographic and electromyographic signals during incremental cycle ergometry. J Electromyogr Kinesiol 11:299–305. doi: 10.1016/S1050-6411(00)00057-2 PubMedCrossRefGoogle Scholar
  59. Potvin JR, Bent LR (1997) A validation of techniques using surface EMG signals from dynamic contractions to quantify muscle fatigue during repetitive tasks. J Electromyogr Kinesiol 7:131–139. doi: 10.1016/S1050-6411(96)00025-9 PubMedCrossRefGoogle Scholar
  60. Richter JM, Mathiassen SE, Slijper HP, Over EAB, Frens MA (2009) Differences in muscle load between computer and non-computer work among office workers. Ergonomics 52:1540–1555. doi: 10.1080/00140130903199905 PubMedCrossRefGoogle Scholar
  61. Rohmert W (1973) Problems with determining rest allowances: part 2. Determining rest allowances in different human tasks. Appl Ergonomics 4:158–162CrossRefGoogle Scholar
  62. Rudroff T, Poston B, Shin I-S, Bojsen-Moller J, Enoka RM (2005) Net excitation of the motor unit pool varies with load type during fatiguing contractions. Muscle Nerve 31:78–87. doi: 10.1002/mus.20241 PubMedCrossRefGoogle Scholar
  63. Sato T, Coury HJ (2009) Evaluation of musculoskeletal health outcomes in the context of job rotation and multifunctional jobs. Appl Ergonomics 40:707–712. doi: 10.1016/j.apergo.2008.06.005 CrossRefGoogle Scholar
  64. Sato H, Ohashi J, Iwanaga K, Yoshitake R, Shimada K (1984) Endurance time and fatigue in static contractions. J Hum Ergol 13:147–154Google Scholar
  65. Seghers J, Spaepen A (2004) Muscle fatigue of the elbow flexor muscles during two intermittent exercise protocols with equal mean muscle loading. Clin Biomech 19:24–30. doi: 10.1016/j.clinbiomech.2003.08.003 CrossRefGoogle Scholar
  66. Shinohara M, Søgaard K (2006) Mechanomyography for studying force fluctuations and muscle fatigue. Exerc Sport Sci Rev 34:59–64PubMedCrossRefGoogle Scholar
  67. Sjøgaard G, Kiens B, Jorgensen K, Saltin B (1986) Intramuscular pressure, EMG and blood flow during low-level prolonged static contraction in man. Acta Physiol Scand 128:475–484PubMedCrossRefGoogle Scholar
  68. Søgaard K, Blangstad AK, Jørgensen LV, Madeleine P, Sjøgaard G (2003) Evidence of long-term muscle fatigue following prolonged intermittent contractions based on mechano- and electromyograms. J Electromyogr Kinesiol 13:441–450. doi: 10.1016/S1050-6411(03)00075-0 PubMedCrossRefGoogle Scholar
  69. Søgaard K, Orizio C, Sjøgaard G (2006) Surface mechanomyogram amplitude is not attenuated by intramuscular pressure. Eur J Appl Physiol 96:178–184. doi: 10.1007/s00421-004-1211-5 PubMedCrossRefGoogle Scholar
  70. Straker L, Mathiassen SE (2009) Increased physical work loads in modern work—a necessity for better health and performance? Ergonomics 52:1215–1225. doi: 10.1080/00140130903039101 PubMedCrossRefGoogle Scholar
  71. Sundelin G, Hagberg M (1989) The effects of different pause types on neck and shoulder EMG activity during VDU work. Ergonomics 32:527–537. doi: 10.1080/00140138908966123 PubMedCrossRefGoogle Scholar
  72. Tanji J, Kato M (1973) Recruitment of motor units in voluntary contraction of finger muscle in man. Exp Neurol 40:759–770PubMedCrossRefGoogle Scholar
  73. Tupling AR (2004) The sarcoplasmic reticulum in muscle fatigue and disease: role of the sarco(endo)plasmic reticulum Ca2+-ATPase. Can J Appl Physiol 29:308–329. doi: 10.1139/h04-021 PubMedCrossRefGoogle Scholar
  74. Ulin S, Armstrong TJ, Snook SH, Keyserling WM (1993) Perceived exertion and discomfort associated with driving screws at various work locations and at different work frequencies. Ergonomics 36:833–846. doi: 10.1080/00140139308967946 PubMedCrossRefGoogle Scholar
  75. Vedsted P, Blangsted AK, Søgaard K, Orizio C, Sjøgaard G (2006) Muscle tissue oxygenation, pressure, electrical and mechanical responses during dynamic and static voluntary contractions. Eur J Appl Physiol 96:165–177. doi: 10.1007/s00421-004-1216-0 PubMedCrossRefGoogle Scholar
  76. Veiersted KB, Westgaard RH, Andersen P (1993) Electromyographic evaluation of muscular work pattern as a predictor of trapezius myalgia. Scand J Work Environ Health 19:284–290PubMedCrossRefGoogle Scholar
  77. Verhagen AP, Karels C, Bierma-Zeinstra SMA, Feleus A, Dahaghin S, Burdorf A, Koes BW (2007) Exercise proves effective in a systematic review of work-related complaints of the arm, neck, or shoulder. J Clin Epidemiol 60:110–117. doi: 10.1016/j.jclinepi.2006.05.006 PubMedCrossRefGoogle Scholar
  78. Visser B, van Dieën JH (2006) Pathophysiology of upper extremity muscle disorders. J Electromyogr Kinesiol 16:1–16. doi: 10.1016/j.jelekin.2005.06.005 PubMedCrossRefGoogle Scholar
  79. Vøllestad NK (1997) Measurement of human muscle fatigue. J Neurosci Methods 74:219–227. doi: 10.1016/S0165-0270(97)02251-6 PubMedCrossRefGoogle Scholar
  80. Vøllestad NK, Sejersted I, Saugen E (1997) Mechanical behavior of skeletal muscle during intermittent voluntary isometric contractions in humans. J Appl Physiol 83:1557–1565PubMedGoogle Scholar
  81. Weir JP, Ayers KM, Lacefield JF, Walsh KL (2000) Mechanomyographic and electromyographic responses during fatigue in humans: influence of muscle length. Eur J Appl Physiol 81:352–359. doi: 10.1007/s004210050054 PubMedCrossRefGoogle Scholar
  82. Wells RP, Mathiassen SE, Medbo L, Winkel J (2007) Time—a key issue for musculoskeletal health and manufacturing. Appl Ergonomics 38:733–744. doi: 10.1016/j.apergo.2006.12.003 CrossRefGoogle Scholar
  83. Westad C, Westgaard RH, De Luca CJ (2003) Motor unit recruitment and derecruitment induced by brief increase in contraction amplitude of the human trapezius muscle. J Physiol 522:645–656. doi: 10.1111/j.1469-7793.2003.00645.x CrossRefGoogle Scholar
  84. Westerblad H, Allen DG (1991) Changes of myoplasmic calcium concentration during fatigue in single mouse muscle fibers. J Gen Physiol 98:615–635. doi: 10.1085/jgp.98.3.615 PubMedCrossRefGoogle Scholar
  85. Westgaard RH, de Luca CJ (1999) Motor unit substitution in long-duration contractions of the human trapezius muscle. J Neurophysiol 82:501–504PubMedGoogle Scholar
  86. Winter DA (2005) Biomechanics and motor control of human movement, 3rd edn. Wiley, New Jersey, pp 230–231Google Scholar
  87. Yassierli, Nussbaum MA (2008) Utility of traditional and alternative EMG-based measures of fatigue during low-moderate level isometric efforts. J Electromyogr Kinesiol 18:44–53. doi: 10.1016/j.jelekin.2006.08.003 PubMedCrossRefGoogle Scholar
  88. Zhang Q, Andersson G, Lindberg LG, Styf J (2004) Muscle blood flow in response to concentric muscular activity vs. passive venous compression. Acta Physiol Scand 180:57–62. doi: 10.1046/j.0001-6772.2003.01215.x PubMedCrossRefGoogle Scholar
  89. Zwarts MJ, Van Weerden TW, Haenen HTM (1987) Relationship between average muscle fibre conduction velocity and EMG power spectra during isometric contraction, recovery and applied ischemia. Eur J Appl Physiol 56:212–216. doi: 10.1007/BF00640646 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Marcus Yung
    • 1
    Email author
  • Svend Erik Mathiassen
    • 2
  • Richard P. Wells
    • 1
    • 3
  1. 1.Department of KinesiologyUniversity of WaterlooWaterlooCanada
  2. 2.Department of Occupational and Public Health Sciences, Centre for Musculoskeletal ResearchUniversity of GävleGävleSweden
  3. 3.Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD)University of WaterlooWaterlooCanada

Personalised recommendations