Here’s some reading on a study of rep ranges for you guys enjoy:
[b]Research on Repetition Ranges
by Wayne L. Westcott, PhD., C.S.C.S.
and Rita La Rosa Loud, B.S.[/b]
According to the American College of Sports Medicine, aerobic activity is necessary to improve cardiovascular endurance and anaerobic activity is necessary to increase muscular strength. Although the recommended duration for aerobic conditioning is relatively long (20 to 60 minutes), no differentiation is discussed with respect to the physiological adaptations. Essentially, we are told that properly performed aerobic exercise anywhere within the prescribed time frame produces the same outcome, namely greater cardiovascular endurance.
While the recommended duration for anaerobic conditioning is relatively brief (less than 90 seconds), different responses are typically proposed by various professional organizations. For example, the American College of Sports Medicine position stand on exercise prescription for muscular strength and endurance is best developed by using lighter weights for a greater number of repetitions.
The National Strength and Conditioning Association suggests more specific relationships between the number of repetitions performed and physiological responses. In their periodization model, they propose that shorter bouts of anaerobic training (2 to 4 repetitions) are best for improving muscle power, moderate bouts of anaerobic training (5 to 6 repetitions) are best for building muscle strength, and longer bouts of anaerobic training (8 to 12 repetitions) are best for increasing muscle hypertrophy. A rough extrapolation of repetitions to time would indicate the following corresponding categories: 10 to 30 seconds of anaerobic exercise for muscle power; 30 to 50 seconds of anaerobic exercise for muscle strength, and 50 to 90 seconds of anaerobic exercise for muscle size. Although apparently arbitrary anaerobic classifications have long been considered as general knowledge and standard procedures by many professionals and textbook authors, there is little research to support these claims.
[b]Study One[/b]
To the contrary, a recent study by Chestnut and Docherty found similar neuromuscular adaptations for previously untrained men (mean age 24 years) training with 4 to 10 repetitions per set. In this study 10 subjects performed 6 sets of 4 repetitions, and 9 subjects completed 3 sets of 10 repetitions in the following core exercises: triceps bench press, triceps pulley pressdown, barbell curl and dumbbell curl. After 10 weeks of training, 3 days per week, the subjects were assessed for changes in 1 repetition maximum (1 RM) strength and muscle size (cross-sectional area). According to the authors, the 4-repetition training and the 10 repetition training elicited statistically significant and equal increases in both muscle strength and muscle size. In other words, the lower repetition training was not better-suited for producing muscle strength and the higher repetition training was not better-suited for increasing muscle size.
While the authors did not report the repetition speed, it is assumed that all sets (4 reps and 10 reps) were completed within the anaerobic energy system (less than 90 seconds). This being the case, these results indicate that shorter and longer bouts of anaerobic exercise produce essentially the same physiological adaptations.
[b]Study Two[/b]
We have also conducted studies comparing lower and higher repetitions per set. The first study, completed in 1991, examined the effects of 10-repetition training and 20-repetition training on muscle strength and muscle endurance.
The subjects in this study were 20 previously untrained men and women (mean age 41 years), who performed one set of the following machine exercises, three days per week, for a period of eight weeks: leg extension, leg curl, chest press, pulldown, shoulder press, seated row, triceps extension and biceps curl. All participants performed 10 leg extensions and 10 leg curls using the heaviest weightload possible (20 RM) with their right leg. Because each repetition was performed in four seconds, the 10 RM set was completed in about 40 seconds and the 20 RM set was completed in about 80 seconds.
The results revealed statistically significant similar increases in muscle strength (1 RM) and muscle endurance (reps with 50 percent of initial 1 RM weightload). More specifically, the 10 RM training produced a 7.6-pound increase in muscle strength and a 7.5-pound increase in muscle strength and a 7.5-pound increase in muscle strength and a 7.5-repetition increase in muscle endurance.
These findings indicated that 40-second and 80-second bouts of anaerobic exercise produce essentially the same physiological changes with respect to muscle strength and endurance. Like Chestnut and Docherty?s study, we found no evidence of differentiated responses associated with lower and higher repetition protocols when training to momentary muscle fatigue within the anaerobic energy system parameters.
[b]Study Three[/b]
During the Winter of 2000, we conducted another study comparing lower and higher repetitions on strength development. This study was designed to replicate our previous research with preadolescents, in which13 to 15 repetitions proved more productive than six to eight repetitions for improving both muscle strength and endurance. We concluded that higher repetition training may be more effective for young boys and girls (mean age 8 years) due to the greater motor learning effect.
The subjects in our adult study were 44 previously untrained men and women (mean age 53 years) who performed one set of the following machine exercises, two or three days per week, for a period of ten weeks: leg extension, leg curl, chest cross, chest press, pullover, lateral raise, biceps curl, triceps extension, low back, abdominal, neck flexion and neck extension. The 22 participants in the low-rep group completed six to eight repetitions of each exercise, and the 22 participants in the high-rep group completed 13 to 15 repetitions of each exercise. Because each repetition was performed in six seconds, a 7 RM set required about 40 seconds and a 14 RM set required about 80 seconds.
The results revealed statistically significant and similar strength gains (7 RM or 14 RM chest press). More specifically, the six to eight repetition trainees made a 14.4-pound weightload increase, and the 13 to 15 repetition trainees made a 15.0-pound weightload increase.
Like our previous adult study, these findings indicated that 40-second and 80-second bouts of anaerobic exercise have almost equal effects on strength development. Like Chestnut and Docherty?s research, both of our adult studies showed no difference in the physiological adaptations associated with lower and higher repetition protocols, when training to momentary muscle fatigue within the anaerobic energy system parameters.
[b]Discussion[/b]
Many strength professionals promote low repetitions with heavier weights for maximizing muscle strength, and high repetitions with lighter weights for developing muscle endurance. However, we are unaware of any research that validates these assumptions. On the other hand, the studies presented in this article showed similar responses in muscle strength, muscle endurance, and muscle size from low-repetition and high-repetition training.
Based on these studies, it would appear that previously untrained adults experience about the same muscular effects from low, medium and high-repetition exercise sets that are completed within the anaerobic energy system (less than 90 seconds).
It may be true that people with a high percentage of fast twitch muscle fibers make greater strength gains with low-repetition training. However, such genetically gifted individuals comprise a very small segment of the population.
In general, most adults may strength train safely and successfully using a wide range of repetitions (e.g., 4 to 20), per set. Based on our professional experience and participant evaluations, we recommend 8 to 12 repetition training. This repetition range corresponds to about 70 to 80 percent of maximum resistance in most strength exercises.
In conclusion, it would appear that training to muscle fatigue within the anaerobic energy system is the essential stimulus for increasing muscle strength, endurance and size, and that these responses are not significantly influenced by low, medium, or high-repetition protocols.
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