Interference Effect of Strength & Hypertrophy
2022 Meta-Analysis – Interference Effect of Strength & Hypertrophy With Concurrent Resistance & Endurance Training: https://pubmed.ncbi.nlm.nih.gov/34757594/ This meta-analysis investigated whether concurrent training (a combination of strength and aerobic exercise) impacts muscle growth and strength gains compared to strength training alone. The researchers synthesized data from 43 studies involving 1,090 participants to assess whether adding aerobic exercise to a strength regimen hinders hypertrophy, maximal strength, or explosive strength. Key findings: - Maximal Strength: Combined training showed a minor effect on maximal strength, with a standardized mean difference (SMD) of -0.06. This suggests minimal interference with maximal strength gains, although studies showed some heterogeneity. - Explosive Strength: Concurrent training showed a moderate reduction in gains for explosive strength and rate of force development, likely due to neuromuscular adaptations affected by aerobic work. - Hypertrophy: Muscle hypertrophy outcomes varied. Most studies indicated that adding aerobic exercise did not significantly impact muscle size when training volumes were carefully managed. However, higher volumes of concurrent training and certain types of aerobic exercises (e.g., cycling over running) had slightly more impact on hypertrophy. Factors like training order, modality, and volume of aerobic exercise played a significant role. Concurrent training in the same session with aerobic exercise first led to slightly more interference, and combining strength and high-frequency aerobic training appeared more disruptive, especially for power adaptations. Interestingly, interference was more noticeable in explosive strength outcomes than in hypertrophy or maximal strength, aligning with findings that low-frequency concurrent training minimizes interference effects on strength and muscle growth. In summary, concurrent training can be structured to minimize interference with strength and hypertrophy gains, though it has a more pronounced effect on explosive strength. The analysis suggests that low-volume aerobic work, especially on separate days or sessions, is preferable for athletes focused on maximal strength and muscle growth while maintaining cardiovascular benefits.