Newmire, DE and Willoughby, DS. Partial compared to full range of motion resistance training for muscle hypertrophy: A brief review and an identification of potential mechanisms. J Strength Cond Res 32(9): 2661-2673, 2018-Resistance training promotes skeletal muscle hypertrophy; there are specific recommendations of intensity, volume, and duration that appear to facilitate hypertrophy the greatest. However, currently, there is not a definitive consensus on optimal range of motion. It appears that the partial range of motion (pROM) mode of exercise may have some similar benefit on muscle hypertrophy as the conventional full range of motion (fROM). Because of the dynamic and multiplanar movement pattern of a multijoint resistance exercise, there may be variation in human force-length and strength-curve theories, which may influence optimal muscle force production at differing portions of a fROM. This suggests specific muscle groups may potentially be optimally recruited during a specific portion of the exercise. The majority of previous research has primarily focused on strength outcomes opposed to muscle hypertrophy. The purpose of this brief review is to highlight the limited and relative pROM literature on muscle hypertrophy and some potential pROM mechanisms that require investigation to assess any plausible relationships. Some potential mechanisms and outcomes of interest are muscle time under tension, muscle activation, and nonuniform hypertrophy. This mode of resistance exercise requires further evaluation on hypertrophic responses; if proven efficacious, it may be employed to those in rehabilitative environments and those that seek more specific regional, local hypertrophic responses such as physique competitors.
The increased popularity of the bikini-physique competitions has not translated to greater research identifying the influence of age on adaptations during contest preparation. The purpose of this case series was to observe how age may influence the adaptations normally seen during preparation and the exploration of newer protocols to address adaptations more relative to the judging standards. Over a 16-week pre-contest preparation, a 32-y bikini competitor (BC) and 44-y master’s bikini competitor (MBC) visited the laboratory bi-weekly to observe changes in body fat mass (BF), lean body mass (LBM), bone mineral density (BMD), total body water (TBW); exploratory measures of deltoid cross-sectional area (DeltCSA), gluteus maximus muscle thickness (GMMT), and subcutaneous adipose tissue thickness (SAT); reproductive hormones estradiol (E2), luteinizing hormone (LH), and energy balance hormones triiodothyronine (T3), leptin and ghrelin; hydration status during contest preparation and the week of competition; resting metabolic rate (RMR); psychometric data related to perceived anxiety, stress, and body image were assessed. No differences between BC and MBC were observed in BF, LBM, BMD, and TBW. Both competitors showed a small loss in LBM. Both BC and MBC showed a contrasting increase in DeltCSA and a loss in GMMT. MBC showed to be slightly more dehydrated (1.025 vs 1.021 g·mL− 1) than BC. Both competitors maintained a euhydration status the day of the competition. No time differences were found between BC and MBC during RMR. BC showed a higher mean difference RMR compared to MBC (2.66 ± 0.75 kcal·kgLBM− 1·d− 1). MBC showed a higher mean difference in LH concentration (84.6 ± 6.01 IU·L− 1), which may be explained by perimenopausal status. MBC had a higher mean difference concentration of leptin (2.51 ± 0.24 ng·mL− 1·kgFM− 1), which was unperturbed by fat loss may be interrelated LH. BC self-reported a higher mean energy intake (15.07 ± 3.43 kcal·kgLBM− 1·d− 1) and higher aerobic training volume (93.26 ± 40.68 min·d). BC and MBC showed similar composition changes, slightly differing metabolic rates, and differing hormonal LH and leptin responses. This finding is in contrast to previous work showing both LH inhibition and leptin diurnal disturbance in younger, female athletes with low energy availability. The exploratory measures may have some benefit for bikini-physique competitors related to the judging criteria. Age did not seem to play a role in contest preparation adaptations.
Bodybuilding is defined as an active lifestyle and competitive interest in body aesthetics and muscularity acquired through resistance training. The overall goal in these cosmetically assessed competitions is to display the human physique in a muscularly proportionate and symmetrical manner. Bodybuilding training falls within the hypertrophic oriented goals and recommendations. However, a resistance training modality known as optimal muscle length-specificity training or partial range of motion (pROM) has been recently investigated and has shown some similar hypertrophic outcomes compared to the standard full range of motion (fROM) resistance training. Additionally, there is some work suggesting pROM may have some benefit in local or regional muscular hypertrophy, which may benefit bodybuilding competitors allowing a muscle group focused stimulus. This may be beneficial for competitors who desire to give more attention to underdeveloped muscle groups to create better proportion and symmetry. There are positive yet not definitive results from investigations of pROM on hypertrophy. More research is needed to assess the validity of this mode of training within this population. Bodybuilding is a competition that judges a physique based on proportionate and symmetrical muscularity. The resistance training modality pROM may have benefits for this population.
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