The Impacts Of Cluster Vs. Traditional Power Training On Physical Performance And Muscle Morphology In Healthy Older Adults

Cluster Resistance Training (CRT) is a training modality primarily used by athletes that employs intra-set rest periods to improve sports performance. However, no studies have examined the effects of CRT on changes in muscle morphology and physical function in older adults. PURPOSE: To compare the effects of cluster (CPT) vs traditional power training (TPT) on changes in muscle morphology including muscle thickness (MT), echo intensity (EI), and pennation angle (PA) of the rectus femoris (RF) and vastus lateralis (VL) and to assess performance changes including: 10 m habitual and maximal gait speeds, 5-time sit-to-stand, timed up-and-go (TUG), seated medicine ball throw, 1-repetition maximum of the chest (CP-1RM) and leg press (LP-1RM), and peak power for the chest (CP-PP) and leg press (LP-PP). METHODS: Participants were recruited from a university population and individuals residing in surrounding neighborhoods. MT, EI, and PA for left and right RF and VL using B-mode ultrasound and physical performance were measured before and after training. RESULTS: For all tests, separate 2 x 2 repeated measures ANOVAs were conducted with pairwise comparisons reported as mean difference ± standard error (MDiff ± SE). For the sample, increases in MT were shown for the right (.194 ± 0.077 cm; p = 0.018) and left (.134 ± 0.049 cm; p = 0.011) RF. For EI of the right VL, a decrease was shown, indicating an increase in muscle quality (-7.421 ± 3.327; p = 0.035). The sample also showed a greater PA for the right VL (1.992 ± 0.845; p = 0.027), which may indicate greater myofibrillar packing and force production. Significant improvements were seen for the sample in the TUG (-.495 ± .117 s; p < .001), CP-1RM (6.153 ± 2.48 kgs; p = .021) and LP-1RM (18.198 ± 5.508 kgs; p = .003), as well as increases in CP-PP (53.077 ± 23.75 W; p = .035) and LP-PP (28.667 ± 12.505 W; p = .032). CONCLUSION: Twice weekly for 12-week CPT and TPT interventions can produce similar improvements in sit-to-stand performance, upper and lower limb strength and power, and quadriceps muscle morphology in older adults. These results indicate no increased improvement in muscle structure or function with the addition of intra-set recovery.