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Individual Region- and Muscle-specific Hamstring Activity at Different Running Speeds

HEGYI, ANDRÁS1; GONÇALVES, BASÍLIO A. M.1,2; FINNI, TAIJA1; CRONIN, NEIL J.1

Medicine & Science in Sports & Exercise: November 2019 - Volume 51 - Issue 11 - p 2274–2285
doi: 10.1249/MSS.0000000000002060
APPLIED SCIENCES
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Introduction Hamstring strain injuries typically occur in the proximal biceps femoris long head (BFlh) at high running speeds. Strain magnitude seems to be the primary determinant of strain injury, and may be regulated by muscle activation. In running, BFlh strain is largest in the proximal region, especially at high speeds. However, region-specific activity has not been examined. This study examined the proximal–distal and intermuscular activity of BFlh and semitendinosus (ST) as a function of increasing running speed.

Methods Thirteen participants ran at steady speeds of 4.1 (slow), 5.4 (moderate), and 6.8 m·s−1 (fast) on a treadmill. Region- and muscle-specific EMG activity were recorded at each speed using high-density EMG, and were normalized to maximal voluntary isometric activity. Muscle–tendon unit lengths were calculated from kinematic recordings. Speed effects, regional, and intermuscular differences were tested with Statistical Parametric Mapping.

Results With increasing running speed, EMG activity increased in all regions of both muscles to a similar extent in the clinically relevant late swing phase. Increases in muscle–tendon unit lengths in late swing as a function of running speed were comparatively small. In fast running, EMG activity was highest in late swing in all regions, and reached 115% ± 20% (proximal region, mean ± 95% confidence limit), 106% ± 11% (middle), and 124% ± 16% (distal) relative to maximal voluntary isometric activity in BFlh. Regional and intermuscular EMG patterns were highly individual, but each individual maintained similar proximal–distal and intermuscular EMG activity patterns across running speeds.

Conclusions Running is associated with highly individual hamstring activity patterns, but these patterns are similar across speeds. It may thus be crucial to implement running at submaximal speeds early after hamstring injury for restoration of normal neuromuscular function.

1Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyvaskyla, FINLAND

2School of Allied Health Sciences, Griffith University, Gold Coast, Queensland, AUSTRALIA

Address for correspondence: András Hegyi, M.Sc., LL175, P.O. Box 35, FI-40014, Jyväskylä, Finland; E-mail: andras.a.hegyi@jyu.fi.

Submitted for publication April 2019.

Accepted for publication May 2019.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.acsm-msse.org).

Online date: June 14, 2019

© 2019 American College of Sports Medicine