Kenny Croxdale
Level 7 Valued Member
PARTIAL RANGE OF MOTION EXERCISE IS EFFECTIVE FOR FACILITATING MUSCLE HYPERTROPHY AND FUNCTION THROUGH SUSTAINED INTRAMUSCULAR HYPOXIA IN YOUNG TRAINED MEN
ABSTRACT
Goto, M, Chikako, M, Hirayama, T, Terada, S, Nirengi, S, Kurosawa, Y, Nagano, A, and Hamaoka, T. Partial range of motion exercise is effective for facilitating muscle hypertrophy and function through sustained intramuscular hypoxia in young trained men. J Strength Cond Res 33(5): 1286–1294, 2019— The acute response to and long-term effects of partial range of motion exercise (PRE) and full range of motion exercise (FRE) of elbow extensors were compared in young trained men. The PRE was expected to increase the intramuscular hypoxic environment, which was theorized to enhance muscular hypertrophy. Forty-four resistance-trained men were divided into 2 training groups, PRE (n = 22) or FRE (n = 22) group, and performed the PRE or FRE acute exercise protocol. The PRE (elbow range from 458 to 908) and FRE (from 08 to 1208) acute protocols consisted of 3 sets of 8 repetitions, with an 8RM, and an equivalent workload. After the initial testing, the training program for each group, comprised 3 training sessions per week for 8 weeks, was started. The acute responses of area under the oxygenated hemoglobin (Oxy-Hb) curve, blood lactate concentration, and root mean square of electromyography were significantly higher both before and after PRE than FRE training. Long-term effects were produced by both PRE and FRE, with significant (p # 0.05) increases in cross-sectional area (CSA) of triceps brachii and isometric strength. The CSA increased significantly greater after PRE (48.7 6 14.5%) than after FRE (28.2 6 10.9%). Furthermore, during the PRE program, a positive correlation was detected between the percent increase in CSA and area under the Oxy-Hb curves before and after 8-week exercise training (before 8-week exercise training: r = 0.59, after 8-week exercise training: r = 0.70, p , 0.01). These results suggest that intramuscular hypoxia might facilitate muscular hypertrophy with PRE being more effective than FRE.
PRACTICAL APPLICATIONS
An 8RM load exercise at the middle range of motion was performed in PRE, and it resulted in acute physiological effects similar to isometric contraction, such as intramuscular hypoxia and higher blood lactate concentration. Furthermore, PRE produced greater increases than FRE in triceps brachii CSA after the 8-week exercise training programs. Therefore, PRE might be a valid training protocol, especially, for well trained individuals with blunted hypoxic muscle stimulation because of long-term resistance training. As it is assumed that weight-bearing and non weight-bearing muscles react differently to a particular exercise (27), the results of this study might be limited to upper extremity muscles.
ABSTRACT
Goto, M, Chikako, M, Hirayama, T, Terada, S, Nirengi, S, Kurosawa, Y, Nagano, A, and Hamaoka, T. Partial range of motion exercise is effective for facilitating muscle hypertrophy and function through sustained intramuscular hypoxia in young trained men. J Strength Cond Res 33(5): 1286–1294, 2019— The acute response to and long-term effects of partial range of motion exercise (PRE) and full range of motion exercise (FRE) of elbow extensors were compared in young trained men. The PRE was expected to increase the intramuscular hypoxic environment, which was theorized to enhance muscular hypertrophy. Forty-four resistance-trained men were divided into 2 training groups, PRE (n = 22) or FRE (n = 22) group, and performed the PRE or FRE acute exercise protocol. The PRE (elbow range from 458 to 908) and FRE (from 08 to 1208) acute protocols consisted of 3 sets of 8 repetitions, with an 8RM, and an equivalent workload. After the initial testing, the training program for each group, comprised 3 training sessions per week for 8 weeks, was started. The acute responses of area under the oxygenated hemoglobin (Oxy-Hb) curve, blood lactate concentration, and root mean square of electromyography were significantly higher both before and after PRE than FRE training. Long-term effects were produced by both PRE and FRE, with significant (p # 0.05) increases in cross-sectional area (CSA) of triceps brachii and isometric strength. The CSA increased significantly greater after PRE (48.7 6 14.5%) than after FRE (28.2 6 10.9%). Furthermore, during the PRE program, a positive correlation was detected between the percent increase in CSA and area under the Oxy-Hb curves before and after 8-week exercise training (before 8-week exercise training: r = 0.59, after 8-week exercise training: r = 0.70, p , 0.01). These results suggest that intramuscular hypoxia might facilitate muscular hypertrophy with PRE being more effective than FRE.
PRACTICAL APPLICATIONS
An 8RM load exercise at the middle range of motion was performed in PRE, and it resulted in acute physiological effects similar to isometric contraction, such as intramuscular hypoxia and higher blood lactate concentration. Furthermore, PRE produced greater increases than FRE in triceps brachii CSA after the 8-week exercise training programs. Therefore, PRE might be a valid training protocol, especially, for well trained individuals with blunted hypoxic muscle stimulation because of long-term resistance training. As it is assumed that weight-bearing and non weight-bearing muscles react differently to a particular exercise (27), the results of this study might be limited to upper extremity muscles.