THE EFFECTS OF BLOOD FLOW RESTRICTION TRAINING ON MUSCULAR SIZE, STRENGTH AND ENDURANCE
INTRODUCTION:Blood flow restriction training, has been utilized by individuals interested in inducing hypertrophic conditions without the use of heavy weight loads. The idea is to restrict venous return while still allowing arterial blood flow into the muscles being occluded. The metabolites built up would then cause an increase in anaerobic conditions producing lactic acid, fatiguing slow twitch fibers and utilizing fast twitch fibers. PURPOSE:The purpose of this study was to compare the effects of blood flow restriction versus standard exercise for hypertrophy, strength, and endurance over a 6 week training period. METHODS: Three men (Age: 23 ±1yrs, Wt: 78.79 ±12.64kg, Ht: 1.72 ±0.07m, Resting SBP: 130.3 ±14.64 mmHg, Resting DBP: 67 ±1.73 mmHg, RHR: 67.6 ±20.6 bpm) and two females (Age: 22.5 ±0.71yrs, Wt: 58.88 ±3.43kg, Ht: 1.63 ±0.04m, Resting SBP: 126.5 ±6.36 mmHg, Resting DBP: 82.5 ±6.36 mmHg, RHR: 89.5 ±7.78 bpm) from the recreational center of UT Arlington were asked to volunteer in the study by face to face contact. Each subject had initial anthropometric data collected along with resting blood pressure andheart rate. Subjects were then assessed to determine a 1 repetition max (1RM) and 10 repetition max (10RM) on their dominant and non-dominant arms during baseline week. For the next 4 weeks, participants were scheduled to meet 2 days/wk on non-consecutive day for training. The training consisted of 5 sets of 10 repetitions 40-50% of their 10RM for their dominant arm, and 5 sets of 10 repetitions of 75-85% of their 10RM for their non-dominant arm. The dominant arm was the arm being occluded at 1.1 times their resting diastolic blood pressure. A 60-second rest period was allowed, with heart rate being measured by using a Polar heart rate monitor every 30 seconds. During the6th week, arm circumference and 1RM were re-taken to measure muscular hypertrophy and strength. In addition, subjects performed repetitions until failure with their initial 10RM to determine changes in muscle endurance. Statistical analysis was done using ANOVA with alpha level set at p ≤ 0.05. RESULTS:Exercise heart rate was 88.87 ±15.76 bpm (occluded) and 102.52 ±15.17 bpm (non-occluded) which demonstrated a significant difference (p = 0.00). Differences in pre-1RM (38.75 ±15.48lbs) and post-1RM (41.25 ±14.9lbs) of the occluded arm approached, but did not reach significance (p = 0.07). However, there was a significance in pre-10RM (10) to failure versus post-10RM (17 ±5.48 reps) to failure of the occluded arm (p = 0.026). Arm circumference of the dominant arm also showed significance (p = 0.025) from pre-(28.05 ±4.48cm) to post-(29.3 ±5.4cm) occlusion. 1RM of the non-occluded, non-dominant arm showed no significance (p = 0.18). Repetitions until failure of the subjects' non-dominant 10RM showed significance (p = 0.01) from pre-training (10) to post-training (17.5 ±4.12 reps). Lastly, changes in non-dominant arm circumferences from pre-training (28.58 ±5.5cm) to post-training (29.5 ±5.58cm) trended toward significance (p = 0.078). CONCLUSION:The results of this study indicate that blood flow restriction training can produce similar or even greater changes in muscular strength, endurance, and mass in healthy populations.