Year of Publication
Master of Science (MS)
Kinesiology and Health Promotion
Dr. Lance Bollinger
Background: As little as three nights of sleep restriction reduces muscle strength. More than one-third of Americans are chronically sleep restricted (< 7.0 hours/night) and are at risk of muscle weakness (dynapenia). Presently, the mechanistic cause of sleep restriction-induced dynapenia (SRID) has not been elucidated. Rapid changes in muscle strength are typically driven by short-term changes in muscle contractility or voluntary recruitment. The purpose of this study was to investigate how sleep restriction affects muscle contractile function and voluntary recruitment. Methods: A sample of 12 subjects (age 24.8 ± 2.6y) underwent isometric and isokinetic knee extensor muscle testing following 3d of adequate sleep (SA; 8.05 ± 0.45h), 3 d of sleep restriction (SR; 5.02 ± 0.05h), and 7d of washout (WO, 8.27 ± 0.50). The morning (7-11a local time) following the last day of each sleep period, subjects performed muscle strength testing using an isokinetic dynamometer. Subjects sat upright with the dominant leg secured at 60⁰ of knee flexion to optimize maximal quadriceps torque. They then performed 3 maximal voluntary isometric contractions (MVICs) of the quadriceps. Then subjects performed 6 submaximal contractions at 15, 30, 45, 60, 75, and 90% of the greatest MVIC. Next, subjects completed an interpolated twitch experiment while on the isokinetic dynamometer to assess voluntary activation. Finally, subjects completed 5 repetitions of isometric contractions, in descending order, at speeds of 300, 240, 180, 120, and 60 degree/s. From these methods we measured the highest MVIC, calculated the voluntary activation (VA), measured twitch properties, and compared the torque-EMG relationship. One-way repeated measures ANOVA were used to compare sleep, MVIC, and VA values, two-way (time x twitch property) repeated measures ANOVA was used to compare twitch properties and the torque-EMG relationship. Results: MVIC torque decreased following SR compared to SA before and after sleep restriction (SA: 217.1 ± 69.4 Nm vs. SR: 199.4 ± 67.1 Nm, p = 0.032). MVIC after WO (219.2 ± 54.2 Nm) was significantly greater than SR (p = 0.018) but was not significantly different from SA (p = 0.991). Although peak isokinetic torque decreased with increasing velocity (p < 0.001), there was no significant effect of sleep or sleep x speed interaction. Peak twitch torque and rate of torque
development, but not relaxation rate, were significantly greater in the potentiated state, but no significant effect of sleep or sleep x time interaction was noted. Sleep 3 condition did not significantly affect voluntary activation (SA: 86.3 ± 11.1% v. SR:86.6 ± 11.9% v. WO 87.7 ± 11.1%; p = 0.695). The torque output at various levels ofelectromyography (EMG) activity was not significantly different among sleep conditions (p = 0.383). The mean power frequency (MPF) of the VL was not significantly different among sleep conditions (p = 0.241). Conclusions: Threenights of sleep restriction decreases knee extensor strength which returns to baseline after 7d of adequate sleep. However, muscle twitch properties and motor unit recruitment are unaffected by 3 nights of sleep restriction. Despite this, sleep extension significantly increased MVIC following a short bout of SR. Future research should focus on the benefits of sleep extension.
Digital Object Identifier (DOI)
Sigrist, Scott, "EFFECT OF SLEEP RESTRICTION ON QUADRICEPS’ STRENGTH AND VOLUNTARY ACTIVATION" (2023). Theses and Dissertations--Kinesiology and Health Promotion. 100.
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