Examining the Effect of Partial-Range of Motion Bench Press Exercise on Metabolic Work, Regional Myoelectrical Amplitude, and Local Muscle Hyperemia: A Pilot Study.

Traditionally, it is recommended to utilize a full-range of motion (fROM) during resistance training; however, recent data has found that using a partial-range of motion (pROM) may elicit similar hypertrophy and strength gains. Further research is required to assess the acute physiological differences of pROM in comparison to traditional fROM during a resistance exercise bout. PURPOSE: The purpose of this pilot study is to observe the metabolic work, myoelectrical amplitude, and muscle hyperemia during and following bouts of both flat and incline barbell bench press exercises with differing ranges of motion. METHODS: One male subject (21.6y; 168cm; 83kg; 20.4%BFat) was randomized to two-bouts flat (FB) and two-bouts of 45°-incline (IB) bench press exercise using either pROM or fROM using a bi-acromial grip width of 200%. For the pROM bouts, an elitefts™ pad was installed on a Smith machine (SM) to control descent distance and the subject was instructed to not fully extend the elbow at the apex of barbell ascension. Seven-days prior to each FB/IB bout, 1RM strength test took place and an MVIC test was administered prior to the FB/IB-bout. The bout intensity was selected to be 75% of 1RM. The subject performed 3 sets and as many repetitions until concentric failure. The SM was equipped with linear position transducer that assessed repetition count, bar height, and displacement (dip). Surface electromyography (sEMG) sensors were placed on the anterior deltoid (AD), pectoralis major-clavicular (PMC), pectoralis major-sternal (PMS), triceps medial (TM), triceps lateral (TL), and an electric joint goniometer was used to assess elbow flexion angle change. Blood lactate (La) samples were captured pre- and post-bout. Ultrasound measures of muscle thickness (MT) and cross-sectional area (CSA) values were collected Pre-, Immediate-post (IP), and 24 h post-bout at 10, 25, 50, and 60% distal to the sternal-clavicular notch. RESULTS: The pROM-FB bout had the highest volume load:12,688 sets·reps·kg, reps: 38, and lowest average ROM distance (20.43 cm); ∆La was highest after fROM-IB (7.8 mmol/L) concurrent with the highest average ROM distance (32.96 cm); pROM-IB ∆La showed the lowest (3.9 mmol/L); MVIC testing using 1RM (MVIC-1RM) for pROM-IB and fROM-IB had values ≤150% compared to standard MVIC (Std-MVIC) ≥150%; no differences were found between MT, CSA, and estimated muscle volume ∆% comparing Pre, IP, and 24 h at 10, 25, 50, 60% between bouts. CONCLUSION: Our current data show that greater volume load does not equate to higher post-bout La concentrations, ROM may influence primary agonist peak sEMG amplitude, yet does not influence greater local post-bout hyperemia, and MVIC-1RM may be a useful tool to capture MVIC

Effects of Resistance Training Status on Exercise Patterns and Body Composition Among Younger and Older Adults

As individuals age, percent body fat tends to increase and lean muscle mass decreases, which may limit the ability to engage in higher intensity exercise. Moderate to vigorous physical activity has been shown to improve body composition, but it is unclear whether exercise patterns, such as amount of moderate and high intensity exercise performed, are impacted by resistance training status in younger and older adults. PURPOSE: To examine whether resistance trained and untrained younger and older adults differ on duration of high, moderate, and low intensity exercise and percent body fat (%BF). METHODS: Younger (23.8 ± 0.4 years) and older (68.5 ± 1.2 years) healthy adults were categorized into 4 groups based on resistance training status: young resistance trained (YT: n = 22), young not resistance trained (YNT: n = 16), old resistance trained (OT: n = 17), and old not resistance trained (ONT: n = 20). Resistance trained participants had been training ≥ 2X per week, for the past ≥ 6 months. Participants completed a survey to assess the intensity and duration of exercise, and a dual x-ray absorptiometry (DEXA) scan was used to determine %BF. The survey asked how many minutes/hours per week participants engaged in high intensity exercise (e.g., jogging, hiking), moderate intensity exercise (e.g., light bicycling, walking briskly), and low intensity exercise (e.g., slow walking, easy yoga). Responses were coded as 1 = none, 2 = 30-60 minutes, 3 = 1-2 hours, 4 = 2-3 hours, 5 = 3-5 hours, and 6 = more than 5 hours. ANOVAs were used to determine group differences for each variable, p ≤ 0.05. Data are reported as mean ± SE. RESULTS: Group differences emerged for high and moderate intensity exercise (p \u3c 0.05), but not for low intensity (p \u3e 0.05). For high intensity, YT (3.64 ± 0.31) was significantly higher than YNT and ONT (YNT: 1.63 ± 0.37, p \u3c 0.001; ONT: 1.55 ± 0.33, p \u3c 0.001), and OT (2.82 ± 0.36) was significantly higher than YNT and ONT (YNT: p = 0.022; ONT: p = 0.010). For moderate intensity, YT (4.91 ± 0.31) was significantly higher than YNT and ONT (YNT: 2.40 ± 0.38, p \u3c 0.001; ONT: 3.52 ± 0.32, p = 0.003), and OT (4.77 ± 0.35) was significantly greater than YNT and ONT (YNT: p \u3c 0.001; ONT: p = 0.011). Also for moderate intensity, ONT was significantly greater than YNT (p = 0.025). For %BF, YT (25.06 ± 2.1%) was significantly lower than YNT and ONT (YNT: 33.55 ± 1.87%, p = 0.001; ONT: 36.47 ± 1.28%, p \u3c 0.001), and OT (29.37 ± 1.11%) was significantly lower than ONT (p = 0.003). All other group comparisons were not different (p \u3e 0.05). CONCLUSION: The older resistance trained individuals did not differ from the younger trained participants on exercise patterns or percent body fat, suggesting the enduring positive effects of resistance training as individuals age. These resistance trained individuals also performed more moderate and high intensity exercise than non-resistance trained groups, likely contributing to their favorable body composition. Funded by Texas American College of Sports Medicine Student Research Development Award to H. Kendall, J. Mettler, and L. Kipp, and Thesis Fellowship Award to H. Kendall