Concurrent strength and endurance training exercise sequence does not affect neuromuscular adaptations in older men

Concurrent training is an effective method for increasing skeletal muscle performance in aging individuals, but controversy exists as to whether chronic neuromuscular and functional adaptations are affected by the intra-session exercise sequence. Therefore the aim of this study was to evaluate the effect of concurrent endurance and power-like strength training exercise sequence on muscular and functional adaptations of older participants. Thirty-six healthy older men not engaged in systematic exercise training programs for at least 6 months were divided into a control group (CON; 65.8 ± 5.3 years), or in the training groups: endurance-strength (ES; 63.2 ± 3.3 years), or strength-endurance (SE; 67.1 ± 6.1 years). Training groups underwent 12 weeks of concurrent endurance and power-like strength training, starting every exercise session with either endurance (in ES) or strength (in SE) exercises. Measurements included knee extension one repetition maximum (1RM), knee extension power, 30 second sit-to-stand test (30SS), maximum vastus lateralis surface electromyographic activity, and rectus femoris echo intensity (RFEI). Significant increases in maximal strength (ES + 18 ± 11.3%; SE + 14.2 ± 6.0%; p ≤ 0.05), peak power (ES + 22.2 ± 19.4%; SE + 26.3 ± 31.3%; p ≤ 0.05), and 30SS performance (ES + 15.2 ± 7.2%; SE + 13.2 ± 11.8%; p ≤ 0.05) were observed only in the training groups, with no differences between ES and SE. Maximum muscular activity was greater after 12 weeks at training groups (p ≤ 0.05), and reductions in RFEI were found only in ES and SE (p ≤ 0.05). These results demonstrate that concurrent strength and endurance training performed twice a week effectively increases muscular performance and functional capacity in older men, independent of the intra-session exercise sequence. Additionally, the RFEI decreases indicate an additional adaptation to concurrent training.