Jie Kang

The Effects of Resistance Exercise Rest Interval Length Manipulation on Exercise Kinetics and Kinematics: A Gender Comparison

PURPOSE: To investigate the effects of different rest interval (RI) lengths on acute resistance exercise performance in men and women. METHODS: Eleven men (age = 22.8 6 6.5 yrs; height = 183.1 6 4.9 cm; body mass = 87.7 6 10.9 kg) and eleven women (age = 20.7 6 4.3 yrs; height = 163.9 6 6.9 cm; body mass = 63.9 6 9.9 kg) performed three protocols consisting of four free-weight exercises using the same sequence (bench press, incline bench press, shoulder press, and bent-over row). The RI of the first exercise (bench press) was manipulated (1-, 2-, and 3-min RI in random order) in order to examine its potential kinetic and kinematic effects on performance of subsequent exercises. Subjects performed 3 sets of each exercise with 75% of their one repetition-maximum (1RM) for up to 10 repetitions. The RI was only manipulated for the bench press and was held constant (2 min) for the remaining three exercises. The number of repetitions completed, bar average power, and velocity for each set of each exercise were recorded using a transducer. RESULTS: Gender differences were observed during performances of the bench press [26.3 6 4.7 versus 21.1 6 3.5 reps (1 min); 28.5 6 2.7 versus 24.0 6 4.5 reps(2 min); and 29.3 6 1.8 versus 25.8 6 5.1 reps (3 min) respectively for women and men] and incline bench press [17.9 6 6.7 versus 13.6 6 4.3 reps (1 min); 19.4 6 8.4 versus 13.1 6 4.3 reps (2 min); and 19.5 6 6.8 versus 13.3 6 6.1 reps (3 min) respectively for women and men] exercises as women performed significantly (P , 0.05) more repetitions (despite the RI length) than men. In both groups, total number of repetitions performed for the incline and shoulder press exercises were significantly lower than the bench press. No differences in total repetitions completed were observed between genders for the shoulder press and bent-over row

Anthropometric and Performance Changes in NCAA Division III College Football Athletes

PURPOSE: To compare anthropometric and athletic performance variables during the playing career of Division III college football players. METHODS: 289 NCAA Division III college football players were assessed for height, body mass, body composition, one repetition-maximum (1-RM) bench press, 1-RM squat, vertical jump height (VJ), vertical jump peak (VJPP) and mean (VJMP) power, 40yd sprint speed (40S), agility, and line drill (LD) over an eight-year period. All testing occurred at the beginning of summer training camp in each of the seasons studied. Data from all years of testing were combined. One-way analysis of variance was utilized to compare performance improvements from the athletes first year of competition to their final year of competition. For most athletes this occurred over four seasons, however for those athletes that redshirted (practiced but did not play) this occurred for five seasons. RESULTS: Players in their 4th and 5th seasons of competition were significantly (p,0.05) heavier than freshmen. No significant changes in body fat were observed during the athlete’s playing career. Significant improvements in strength were seen in both the 1-RM bench press and squat from the first (117.4 6 20.9 kg and 152.5 6 27.3 kg, respectively) to second (126.7 6 20.4 kg and 166.4 6 28.4 kg, respectively) season and from the second to third year (134.5 6 21.7 kg and 179.8 6 30.4 kg, respectively). No strength improvements were seen between the third and fourth year of competition, but athletes playing a fifth year gained significant strength during their final year of competition in both exercises (153.8 6 21.2 kg and 207.4 6 35.1 kg, respectively). VJ was significantly different during the fourth season compared to the first, second and third seasons. VJPP and VJMP were significantly greater between the first (9181 6 556 W and 2127 6 320 W, respectively) and second year (9352 6 559 W and 2206 6 321 W, respectively), and improved during the fourth season (9714 6 631 W and 2377 6 368 W, respectively). No changes in 40S, agility or LD time were seen during the athletes playing career. Fatigue rate for the LD significantly improved from the first (83.4 6 6.4%) to second season (85.1 6 6.5%). No improvements were seen between the second and third seasons in fatigue rate but, significant greater fatigue rates were seen in the fourth (88.3 6 4.8%) and fifth (91.2 6 5.2%) seasons. CONCLUSIONS: Strength and power performance improvements appear to occur throughout the football playing career of NCAA Division III athletes. However, the ability to significantly improve speed and agility was limited. Practical Applications: Although strength and power can be significantly improved by strength and conditioning programs during an athlete’s playing career, speed and agility performance may be dependent more on genetic factors than by training adaptations.