Maximal Strength Assessments

Upper- and lower-body strength was assessed by 1RM testing in the barbell parallel back squat (1RM_SQUAT) and flat barbell bench press (1RM_BENCH) exercises. These exercises were chosen because they are well established as measures of maximal strength. Subjects reported to the laboratory having refrained from any exercise other than activities of daily living for at least 48 h before baseline testing and at least 48 h before testing at the conclusion of the study. RM testing was consistent with recognized guidelines established by the National Strength and Conditioning Association (14). In brief, subjects performed a general warm-up before testing that consisted of light cardiovascular exercise lasting approximately 5 to 10 min. A specific warm-up set of the given exercise of 8 to 10 repetitions was performed at ~50% of subjects’ perceived 1RM followed by one to two sets of two to three repetitions at a load corresponding to approximately 60% to 80% 1RM. Subjects then performed sets of one repetition of increasing weight for 1RM determination. Three- to 5-min rest was provided between each successive attempt. All 1RM determinations were made within five trials. Subjects were required to reach parallel in the 1RM_SQUAT for the attempt to be considered successful as determined by a squat beeper (SquatRight); confirmation of squat depth was obtained by a research assistant positioned laterally to the subject to ensure accuracy. Successful 1RM_BENCH was achieved if the subject displayed a five-point body contact position (head, upper back, and buttocks firmly on the bench with both feet flat on the floor) and executed full-elbow extension. 1RM_SQUAT testing was conducted before 1RM_BENCH with a 5-min rest period separating tests. Recording of foot and hand placement was made during baseline 1RM testing and then used for poststudy performance. All testing sessions were supervised by the research team to achieve a consensus for success on each trial. The repeatability of strength tests was assessed on two nonconsecutive days in a pilot study of six young, resistance-trained men. The ICC for the 1RM_BENCH and 1RM_SQUAT was 0.98 and 0.93, respectively. The SEM for these measures are 2.0 and 2.4 kg, respectively.

Upper-body muscular endurance was assessed by performing the bench press using 50% of the subject’s initial 1RM in the bench press (50% BP) for as many repetitions as possible to momentary failure with proper form. Successful performance was achieved if the subject displayed a five-point body contact position (head, upper back, and buttocks firmly on the bench with both feet flat on the floor) and executed a full lock-out. Muscular endurance testing was carried out after assessment of muscular strength to minimize effects of metabolic stress interfering with performance of the latter. The repeatability of the muscular endurance test was assessed on two nonconsecutive days in a pilot study of seven young resistance-trained men. The ICC for the 50% BP was 0.93, and the SEM was 0.99 repetitions.