Physical Activity Participation, Muscle Architecture And Movement Velocity During Resistance Exercise

Components of muscle architecture are muscle thickness (MT), fascicle length (FL) and pennation angle (PA). Longer FL is associated with speed and power, while greater PA is associated with greater muscle force production. However, there is a paucity of published data comparing the relationship between muscle architecture and concentric movement velocity (CMV) based on the type of physical activity participation during resistance exercise (RE). Purpose: This study aimed to compare the effects of recreational physical activity participation on muscle architecture and CMV during resistance exercise (RE). Methods: Twenty-four males (21 ± 1.8 years) were placed into a recreationally active aerobic (RAA) group (N = 6) or a recreationally active resistance exercise (RAR) group (N = 18) based on self-report types and quantities of physical activity. All subjects completed a right leg, single-leg leg extension at 75% and 90% of 1-repetition maximum (1RM) to failure. CMV was measured using an ultrasound sensor and custom-built software. Ultrasound measurements of the right vastus lateralis (VL) were taken to assess PA, MT and FL. Results: PA and FL were significantly correlated with 75% peak and average CMV (r = 0.41-0.75; p < 0.05). MT was moderately correlated with 1RM (r = 0.32), while FL exhibited a moderate correlation with MT (r = 0.624) and a strong correlation with PA (r = -0.80). RAA and RAR exhibited no significant differences between the groups for MT and 1RM (p > 0.05). RAR exhibited significantly faster 75% peak (0.58 ± 0.09 m/s vs 0.47 ± 0.07 m/s) and 90% average (0.30 ± 0.07 m/s vs 0.22 ± 0.07 m/s) CMV. Additionally, RAR exhibited a trend toward a faster 75% average (0.35 ± 0.07 m/s vs 0.29 ± 0.08 m/s; p = 0.070) and 90% peak (0.53 ± 0.12 m/s vs 0.42 ± 0.15 m/s; p = 0.077) CMV. However, RAA exhibited significantly greater PA (13.7 ± 0.7o vs 11.5 ± 1.2o; p < 0.01) and significantly smaller FL (11.79 ± 0.75 cm vs 14.54 ± 2.15 cm; p < 0.01). Conclusion: Both longer FL and smaller PA resulted in greater peak and average CMV during moderate-to-intense RE. The RAR group exhibited longer FL and smaller PA, when compared to the RAA group. Muscle architecture (i.e., FL and PA) may adapt or remodel to meet the demand of specific types of physical activity or training.