Many involved in the pursuit of weight training to develop strength and lean muscle mass (power lifters, bodybuilders, and athletes) have long utilized partial repetitions in their training. Only recently, however, has scientific interest in this training technique been demonstrated. A limited but growing amount of research has been done in the area of partial range of motion exercise (5, 8, 11, 15). This investigation focused on the use of partial range of motion training and its effectiveness in promoting the development of overall range of motion strength. The focus on strength development in this study was due to 2 factors. First, research in this area indicates that training of relatively short duration (8–10 weeks) produces only minimal gains in muscular size or the development of lean muscle mass (2, 3, 9). Second, there is evidence that suggests there is a strong neuromuscular adaptation that occurs with the partial range of motion technique (17).
A recent method utilized in strength training and one that has indicated great promise is the use of supermaximal loads through the strongest range of motion. The strongest range of motion has been determined to be beyond the sticking point in the upper portion of the lift (4, 10, 17–19). For the bench press, which will be the focus of this investigation, this has been determined to be near full extension of the elbows (4, 10). This would roughly be considered the final 2 to 5 inches of the lift. Loads used in this type of training often exceed 100% of an individual's 1 repetition maximum (1RM) (11).
Zatsiosky (19), an architect of the Soviet Union's success in Olympic and international competition, refers to the effectiveness of this method of training in his book. This lifting technique is purportedly based on Zatsiosky's work with athletes prior to the fall of the Soviet Union. Known as the accentuation principle, this concept states that training should take place in the limited range of motion that demands maximal force production. Wilson (17) believed that adaptation involving this type of training occurs because of a decreased neural inhibition in response to the extreme loads utilized.
Sisco and Little (14) make numerous assertions related to this method of training. These investigators convey the theory that partial range of motion movements using heavy weights are superior to full range of motion movements for developing strength and muscular size. This idea is in direct conflict with most experts in the field that insist that weightlifting should be done through the full range of motion and that no practical benefits can be derived from partial movements (3, 13, 16). Interestingly, Sisco and Little (14) make a strong case in support of their position. They provide convincing anecdotal information and supposed testimonials on the use of partial repetitions by famous strong men. However, the research data they provide are limited.
While the data related to Sisco and Little's (14) work is sparse, other researchers provide information significant to this area of inquiry. Jones et al. (8) incorporated 1 set of partial repetitions in their study investigating the relationships between maximum concentric acceleration and the development of strength and power. The researchers indicated that the partial repetitions may have been a factor in the strength and power development reported, and recommended the training method receive further scrutiny.
Sullivan et al. (15) investigated whether restricted range of motion weight-training exercise would accentuate the cardiovascular response compared to full range of motion movements. The barbell curl was the exercise utilized in this investigation. The researchers found that the restricted range of motion exercise produced significantly increased heart rate, blood pH and lactate levels, and rate of perceived exertion as compared to the full range of motion movements. A biomechanical analysis was also conducted in conjunction with this study. These findings indicated that greater torque was produced by the restricted range of motion movement as opposed to the full range of motion movement. The researchers hypothesized that the restricted range of motion increases the rate of movement, thereby increasing the work performed for a given period of time, resulting in a greater training effect.
Mookerjee and Ratamass (11) investigated strength differences following an acute exposure to full and partial range of motion bench press exercise. Subjects were tested on the 1RM and the 5 repetition maximum (5RM) for both the partial and the full range of motion movements. The results of the study indicated that the partial range of motion performance increased significantly for both the 1RM and the 5RM, while no such improvement was observed for the full range of motion movements. The researchers suggested that this improvement might have occurred because of a motor learning response and improved coordination of both primary and stabilizing muscles involved in the activity.
Mookerjee and Ratamass (11) hypothesized that those individuals who trained exclusively with a full range of motion might fail to optimally train in the area where maximal force development occurs. They speculated that partial range of motion exercise allows optimal force production to occur because of the elimination of the sticking point, thus giving the lifter a biomechanical advantage. The researchers based this conclusion on the fact that subjects were able to use greater loads in the partial movements than in the full range of motion movements. These findings seem to support Sullivan et al. (15), who reported greater torque production during performance of partial range of motion barbell curls.
Other than the limited empirical data associated with partial range of motion training, there are several limitations to this body of research. First, the studies in this area frequently involved only limited training protocols. Second, previous investigations involved only a small number of subjects. Third, in several of these investigations, partial range of motion training was only a small aspect of the research and was not the primary focus of the study. Finally, the length of training time involved in these studies was often of extremely short duration. Because of these limitations, a study was planned to corroborate or contradict the partial range of motion theorists.
Experimental Approach to the Problem
The investigation covered a 10-week period. As previously mentioned, the bench press was used as the criterion measurement. Subjects were divided into 3 groups. The first group (N = 11) trained with 3 full range of motion sets on the bench press. A second group (N = 15) trained with 3 partial range of motion sets. A partial repetition was defined as one that is beyond the sticking point, 2–5 inches from full extension of the elbows (4, 10, 11, 14, 18). A third group (N = 30), which served as a quasi control, trained with a combination of partial and full range of motion sets. To equalize the 2 combinations, this group performed 2 partial range of motion sets and 1 full range of motion set for the first 5 weeks. For the next 5 weeks, this regimen was reversed and the subjects performed 1 partial range of motion set and 2 full range of motion sets. Supervisory personnel who conducted the training were all instructed in the training protocol prior to the investigation (14).
Training sessions were conducted 2 days per week. All bench press protocols incorporated 3 sets of 15 repetitions. When subjects completed the prescribed number of sets and repetitions on any of the exercises performed in the study, they were allowed to increase the weight by 5 pounds in the next training session. Beginning weight for the bench press was determined by a 1RM as prescribed by Baechle (1). The full range of motion group initially trained with sets of 65% of their 1RM. The partial range of motion group began the study training with sets at 100% of their 1RM. In addition to being tested at the beginning of the study, subjects were also posttested on the 1RM at the end of the 10th week. This test has been found to have a reliability of 0.93 (7). Except for the bench press, all subjects engaged in the same training routine during the duration of the investigation (Table 1).
Subjects were not allowed to do any other weighttraining activities outside the perimeters of the study. A 2/4 format was used to perform the full range of motion repetitions. The weight was lowered in 4 seconds and raised in 2 seconds (3). Because of the restricted nature of the partial range of motion repetitions, the individual's natural lifting speed was utilized. A rest period of 2 minutes was permitted between sets (1, 3).
The subjects (N = 56) for this study consisted of men college students participating in university weight-lifting classes. Subjects were recreational weightlifters who had some experience in the activity of weight training. These individuals ranged from those who worked frequently at moderately high levels of intensity to those who worked out occasionally or infrequently. Those involved in intercollegiate athletics or bodybuilding were excluded. Those who reported use of performance-enhancing drugs were also excluded. Permission for the use of human subjects in this investigation was obtained through both the University of Southern Mississippi and the University of Alabama.
A t-test was used to determine differences within each of the group's posttreatment. Because of the pretest variations between groups on the 1RM, a univariate analysis of covariance (ANCOVA) was utilized to assess differences between the 3 groups’ posttreatment. Statistical significance on both analyses was identified as being at a Bonferroni corrected p ≤ 0.0125 level.
The strength levels, as measured by the 1RM for each of the 3 groups, increased from pre- to posttest. A t-test indicated that the increase for each of the groups was statistically significant (Table 2). The full and partial range of motion groups experienced almost identical mean increases of 25 and 24.33 pounds, respectively, while the combination group's mean increased 16.50 pounds. The means and standard deviations for the 3 groups’ pre- and post-1RM are included in Table 3. An ANCOVA was conducted to determine if any meaningful differences existed between the groups. None was found (Table 4).
If the hypothesis that overload is the single most important determinant involved in strength development is correct, then those who engage in partial repetitions should experience the greatest levels of strength development. This was not the finding of this investigation. In fact, no discernable strength differences were found between any of the 3 groups at the conclusion of the study. Most traditional experts in the field have long held that partial repetitions provide no benefit to the serious weightlifter. Again, this was not the finding of this investigation, at least as far as the development of maximal strength was concerned. Partial and mixed repetitions were found to be equally as effective as full repetitions within the parameters of this study.
To this end, at least 2 rival hypotheses can be drawn from these findings. First, if partial range of motion training cannot be demonstrated to be superior to full range of motion training, why not advocate full repetitions? The argument can be made that the benefits of increased flexibility and decreased susceptibility to injury provided by full range of motion repetitions preclude the use of partial range of motion repetitions as a practical training option. The second possible hypothesis is if partial range of motion training is just as effective as full range of motion training, why not advocate the partial technique as a supplement or aid in overcoming training plateaus or as an adjunct to full range of motion training? This research appears to give some support to the second contention.
The role that heavier weights associated with the partial range of motion technique plays in strength increases through a full range of motion was not completely discerned from this investigation. However, because of the length of the study, gains in muscle mass from the training protocol could be expected to contribute only minimally to the strength increases observed (2, 3, 9). This implies there is a neuromuscular adaptation involved that can positively influence strength increases over the full range of motion. It does appear beyond question that, at the very least, training at the top end of the training movement does increase strength within that specific range of motion (5, 6, 10, 17). This, for example, would appear to be of benefit to power lifters as they attempt to lock a weight out at the top of the lift. Similarly, other athletes who must demonstrate strength in the upper portion of their range of motion would also seem to benefit from the partial range of motion technique. This reasoning suggests support for those researchers who assert that utilizing partial range of motion exercise in addition to more traditional weight-training practices assists individuals to reach their maximum strength potential (11, 17, 19).
While the results of this study found no differences between the 3 training regimens, additional research in this area is needed to establish the potential of partial range of motion training. It may eventually be demonstrated that this technique has only limited applications. However, further scrutiny possibly could yield different findings. Advanced weightlifters, with more experience in the bench press, may be more accustomed to pushing themselves closer to their physiological limits, making partial range of motion exercise an even more viable training option. Also, a person who has been training with weights for a longer period of time and has reached a plateau where little or no increases in strength are occurring may be in a better position to benefit from the partial range of motion technique. This hypothesis is supported by Mookerjee and Ratamess (11). Therefore, because of these considerations, it is recommended that future studies be conducted to investigate this phenomenon.
Today, individuals in our society are constantly bombarded with new concepts and information. This phenomenon can often be overwhelming. It is often difficult for the modern person to know what information has practicality and what should be discarded. The strength and conditioning professional is no different. Those working with athletes or the general public need valid and reliable data that they can utilize in structuring viable and effective training programs. It is the obligation of the scientific community within the profession to provide the frontline practitioner with this information. The adoption of training techniques without proper evaluation has plagued our field for generations (12). It is only through exhaustive research that we can keep from making the mistakes of the past. This research project provides some insight into the practical application of the partial range of motion technique. However, further research in this area is needed to elucidate its proper place in an overall training regimen. Consequently, it is recommended that further investigations using this technique be conducted with different populations, different training exercises, larger N sizes, and longer training periods. It is hoped that this research adds to the body of knowledge in this area.
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