LED Therapy for Muscle Growth: Strength Training in 8-Weeks
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Time to read 5 min
The quest for methods to enhance strength training outcomes has spurred interest in various therapies, including Low-Energy Laser Therapy (LEDT). This study examines the effects of LED Therapy for muscle strength performance compared to sham LEDT and a control group over eight weeks. By measuring one-repetition maximum (1RM) strength and elbow flexion-extension repetitions, the research seeks to determine whether LEDT can significantly boost strength gains when integrated into training regimens. Utilizing robust statistical analyses, this investigation not only elucidates the potential benefits of LEDT in muscle development but also addresses its implications for athletes and rehabilitation practices.
Description
The study investigates the effects of low-energy laser therapy (LEDT) effects on strength training outcomes compared to sham LEDT and a control group. Over eight weeks, participants were evaluated for their one-repetition maximum (1RM) strength and elbow flexion-extension repetitions. The research assesses whether LEDT can significantly enhance strength gains and performance when integrated into a training regimen. Utilizing repetitive measures and statistical analyses, the investigation provides insights into the effects of LED Therapy for muscle strength and the implications for its use in sports and rehabilitation
Source
DOI: 10.1519/JSC.0000000000002021
Summary: LED Therapy for Muscle Strength Training
The Journal of Strength & Conditioning Research33(2):433-442, February 2019.
This clinical trial investigated the effects of low-energy laser therapy (LEDT) on strength training outcomes over eight weeks, comparing its efficacy with sham LEDT and a control group. Participants were evaluated for one-repetition maximum (1RM) strength and elbow flexion-extension repetitions at baseline and after 2, 4, 6, and 8 weeks. The results indicated significant strength gains in the LEDT group, which recorded a mean 1RM increase of 30.4 kg (mean ± SD = 12.4 kg), whereas the sham LEDT and control groups showed increases of 20.1 kg (7.5 kg) and 1.2 kg (4.0 kg), respectively. These differences were statistically significant (p < 0.001), and post hoc tests confirmed significant differences among all three groups.
The percent change from baseline revealed an average increase of 87% (± 44%) in the LEDT group, compared to 79% (± 59%) for the sham LEDT group and just 3% (± 10%) for the control group. A repeated-measures ANOVA showed a significant interaction effect between time and group (p = 0.02), indicating that LEDT facilitated faster strength gains than sham LEDT. While both LEDT groups experienced a decline in elbow flexion-extension repetitions over time—likely due to increased training load—age was identified as a significant factor influencing performance. Functional independence measures showed no significant changes across groups.
In conclusion, the findings suggest that LEDT significantly enhances strength training outcomes and could be effectively integrated into training protocols for athletes and those in rehabilitation. The research highlights the potential benefits of LEDT in muscle development and underscores the importance of considering age-related factors in training interventions. Future studies are recommended to explore long-term effects, optimal dosing, and the biological mechanisms underlying these outcomes.
Surface Electromyography Data Analysis and Fatigue Index
In the clinical trial, surface electromyography (SEMG) data was analyzed to assess muscle fatigue by calculating the Fatigue Index (FI) before and after an eight-week training period. The SEMG raw signal was recorded for 30 seconds at baseline and again at the end of the trial, with data analyzed in 10-second intervals. The Median Frequency (MDF) of the first and third 10-second windows was used to compute the FI by dividing the MDF of the third window by that of the first. This method was also applied to the control group, which did not undergo strength training during the study period. The FI approach was selected due to its improved reliability in measuring muscle fatigue, particularly in the quadriceps femoris, as evidenced in prior research.
Statistical Analyses
The statistical analyses in this clinical trial employed various methods to compare the three groups based on age, body mass, and height, which could affect the results. An analysis of variance (ANOVA) was conducted to assess these demographic variables. For one-repetition maximum (1RM) elbow flexion-extension, percent change from baseline to the eight-week mark was calculated using the formula:
(final value−baseline value)/baseline value×100%
(final value−baseline value)/baseline value×100%.
A one-way ANOVA was then used to compare the mean differences across the three groups. For the LEDT groups, a repeated-measures ANOVA was used to evaluate changes over time at five intervals (baseline, 2, 4, 6, and 8 weeks), incorporating both group and time factors while controlling for age. The total number of elbow flexion-extension repetitions and the Fatigue Index (FI) were analyzed similarly using repeated-measures ANOVA, but with fewer time points (initial and 8-week follow-up). A significance level of 0.05 was set for all tests without adjustments for multiple comparisons due to the preliminary nature of the study. Analyses utilized SPSS 24 and R Studio Version 0.98.1083.
Result
Anthropometric Characteristics
- No differences were found between the groups in anthropometric characteristics (details in Table 1).
1RM Load Results
- Mean Differences in 1RM (baseline to end of week 8):
- LEDT Group: 30.4 kg (mean ± SD = 12.4 kg)
- Sham LEDT Group: 20.1 kg (7.5 kg)
- Control Group: 1.2 kg (4.0 kg)
- Statistical analysis:
- Groups were statistically different (p < 0.001).
- Post hoc tests indicated all three groups differed significantly.
Percent Change from Baseline
- LEDT Group: 87% (± 44%)
- Sham LEDT Group: 79% (± 59%)
- Control Group: 3% (± 10%)
- Overall comparison significant (p < 0.001).
- LEDT and sham LEDT did not differ; both were different from the control group.
Repeated-measures ANOVA
- An interaction between time and group was observed (p = 0.02) adjusting for age.
- Interpretation focused on the interaction, with LEDT showing a faster increase in 1RM over time compared to sham LEDT.
Elbow Flexion-Extension Repetitions
- Results shown in Table 3:
- Significant factor: Age (p = 0.04).
- No significance for time (p = 0.58), group (p = 0.20), time by age (p = 0.48), or time by group (p = 0.95).
- Both LEDT groups showed a decrease in repetitions over time, likely due to increased training load.
Functional Independence Measures (FIs)
- No significant differences observed:
- Mean change in FI (p = 0.31) and percentage change (p = 0.40).
Conclusion
The findings of this study suggest that low-energy laser therapy (LEDT) can significantly enhance strength training outcomes compared to sham LEDT and control conditions. The LEDT group demonstrated notable increases in 1RM strength and percentage changes from baseline, indicating its effectiveness in promoting muscular strength through integration into training protocols. Both LEDT and sham LEDT groups exhibited better performance than the control group over the eight weeks, highlighting the potential of LEDT in muscle development and recovery.
Moreover, despite a decline in elbow flexion-extension repetitions in both LEDT groups, the impact of age on performance underscores the importance of tailoring interventions to individual characteristics. The significant interaction observed indicates that LEDT may facilitate faster strength gains, differentiating it from sham treatment. Overall, this research contributes valuable insights into the role of LEDT in strength training and its implications for athletes and rehabilitation contexts. Future studies should explore long-term effects, optimal dosage, and underlying biological mechanisms to understand better how LEDT can maximize training outcomes and enhance recovery.
