Does Photobiomodulation Therapy Enhance Maximal Muscle Strength and Muscle Recovery?

AbstractPhotobiomodulation has been shown to improve tissue and cell functions. We evaluated the influence of photobiomodulation, using a B-Cure laser, on: 1) maximal performance, and 2) muscle recovery after resistance exercise. Two separate crossover randomized double-blinded placebo-controlled trials were conducted. Sixty healthy physical education students (28 men, 32 women), aged 20-35, were recruited (30 participants for each trial). Participants performed two interventions for each experiment, with real lasers (GaAlAs, 808 nm) on three quadricep locations in parallel (overall treatment energy of ~150J) or sham (placebo) treatment. In the first experiment muscle total work (TW) and peak torque (PT) were measured by an isokinetic dynamometer in five repetitions of knee extension, and in the second experiment muscle recovery was measured after the induction of muscle fatigue by evaluating TW and PT in five repetitions of knee extension. There were no differences between treatments (real or sham) regarding the TW (F(1,28) = 1.09, p = .31), or PT (F(1,29) = .056, p = .814). In addition, there was no effect of photobiomodulation on muscle recovery as measured by the TW (F(1,27) = .16, p = .69) or PT (F(1,29) = .056, p = .814). Applying photobiomodulation for 10 min immediately before exercise did not improve muscle function or muscle recovery after fatigue.

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Ability of Isokinetic Dynamometer to Predict Isotonic Knee Extension 1-Repetition Maximum

Journal of Sport Rehabilitation ◽

10.1123/jsr.2018-0396 ◽

2020 ◽

Vol 29 (5) ◽

pp. 616-620

Author(s):

Joseph B. Lesnak ◽

Dillon T. Anderson ◽

Brooke E. Farmer ◽

Dimitrios Katsavelis ◽

Terry L. Grindstaff

Keyword(s):

Resistance Training ◽

Knee Injury ◽

Peak Torque ◽

Knee Extension ◽

Prediction Equation ◽

Isokinetic Dynamometer ◽

Physically Active ◽

Repetition Maximum ◽

Knee Rehabilitation ◽

Torque Values

Context: Resistance training exercise prescription is often based on exercises performed at a percentage of a 1-repetition maximum (1RM). Following knee injury, there is no consensus when a patient can safely perform 1RM testing. Resistance training programs require the use of higher loads, and loads used in knee injury rehabilitation may be too low to elicit gains in strength and power. A maximum isometric contraction can safely be performed during early stages of knee rehabilitation and has potential to predict an isotonic knee extension 1RM. Objective: To determine whether a 1RM on an isotonic knee extension machine can be predicted from isometric peak torque measurements. Design: Descriptive laboratory study. Setting: University research laboratory. Participants: A total of 20 (12 males and 8 females) healthy, physically active adults. Main Outcome Measures: An isokinetic dynamometer was used to determine isometric peak torque (in N·m). 1RM testing was performed on a knee extension machine. Linear regression was used to develop a prediction equation, and Bland–Altman plots with limits of agreement calculations were used to validate the equation. Results: There was a significant correlation (P < .001, r = .926) between peak torque (283.0 [22.6] N·m) and the knee extension 1RM (69.1 [22.6] kg). The prediction equation overestimated the loads (2.3 [9.1] kg; 95% confidence interval, −15.6 to 20.1 kg). Conclusions: The results show that isometric peak torque values obtained on an isokinetic dynamometer can be used to estimate 1RM values for isotonic knee extension. Although the prediction equation tends to overestimate loads, the relatively wide confidence intervals indicate that results should be viewed with caution.

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The Reliability of Four Different Methods of Calculating Quadriceps Peak Torque and Angle-Specific Torques at 30°, 60°, and 75°

Journal of Sport Rehabilitation ◽

10.1123/jsr.2.4.243 ◽

1993 ◽

Vol 2 (4) ◽

pp. 243-250 ◽

Cited By ~ 6

Author(s):

Brent L. Arnold ◽

Dawid H. Perrin

Keyword(s):

Intraclass Correlation ◽

Correlation Coefficients ◽

Peak Torque ◽

Knee Extension ◽

Eccentric Contractions ◽

Isokinetic Dynamometer ◽

Intraclass Correlation Coefficients ◽

Best Value

Twelve university females were studied to determine the reliability of four different methods of calculating concentric and eccentric peak torque (PT) and angle-specific torques (ASTs) for knee extension. Each subject was tested on the Kin-Corn isokinetic dynamometer on two separate occasions, performing five concentric and eccentric contractions at 60° • s−1. PT and AST at 30°, 60°, and 75° were calculated by averaging the first three contractions, averaging all five contractions, taking the single best value of the first three contractions, and taking the single best value of all five contractions. Intraclass correlation coefficients derived from these calculations showed high correlation among the four methods. Additionally, z tests performed on correlation coefficients transformed to Fisher's Z revealed no differences between pairs of correlation coefficients. These data appear to show there is no difference among the four methods of calculating PT and AST.

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