Portal de Periódicos da CAPES

Backpack Hip Strap Use on Oxygen Consumption, Blood Pressure and Muscle Oxygen Saturation While Walking

2019; Lippincott Williams & Wilkins; Volume: 51; Issue: 6S Linguagem: Inglês

10.1249/01.mss.0000561326.03585.83

1530-0315

Peter A. Hosick, R. Delgado, Angelica Del Vecchio, William J. Sullivan, Evan L. Matthews,

Occupational Health and Performance

Previous work has shown that energy expenditure increases while carrying a loaded backpack. However, few investigations have focused on the impact of utilizing a hip strap. PURPOSE: To determine if using a backpack hip strap (HS) has any physiological effects while walking. METHODS: Thirteen subjects (23 ± 4.8 yrs; 5 females, 8 males) walked for 30 mins on a treadmill with a backpack containing 30% of the subject's bodyweight at a 3% grade and speed eliciting 40-50% of their heart rate reserve. Two trials were performed: without a HS (UnST) and with HS (ST). Heart rate (HR), oxygen consumption (VO2), systolic blood pressure (SBP), and oxygen saturation of the quadriceps (Q SmO2) and calf (C SmO2) were measured throughout each trial. Five minute averages were calculated for HR, VO2, Q SmO2 and C SmO2 at baseline (BL), mins 0-5, 6-10, 11-15, 16-20, 21-25, and 26-30. SBP was analyzed as a change score from baseline. A repeated measures ANOVA was used to evaluate the differences between trials at each time point. RESULTS: HR at mins 0-5 (UnST: 121 ± 4 bpm; ST: 120 ± 3 bpm) was elevated (p<0.001) compared to BL (UnST: 81 ± 4 bpm; ST: 80 ± 4 bpm) and remained elevated from BL for the remainder of the trial. All other HR measures were similar with no difference between trials (p=0.912). VO2 at mins 0-5 (UnST: 1.6 ± 0.1 L/min; ST: 1.5 ± 0.1 L/min) was elevated (p<0.001) compared to BL (UnST: 0.38 ± 0.02 L/min; ST: 0.38 ± 0.03 L/min), but was similar to all other time points with no difference between trials (p=0.317). The change in SBP at mins 0-5 (UnST: 26 ± 8 mmHg; ST: 31 ± 6 mmHg) was similar to all other time points (p=0.115) and did not differ between trials (p=0.224). Q SmO2 at mins 11-15 (UnST: 87 ± 3 %; ST: 84 ± 4 %) was higher compared to BL (UnST: 78 ± 3 %; ST: 79 ± 4 %; p=0.040) and remained elevated for the remainder of the trial with no difference between trials (p=0.515). C SmO2 at mins 0-5 (UnST: 55 ± 6 %; ST: 47 ± 7 %; p<0.001) was lower compared to BL (UnST: 72 ± 4 %; ST: 74 ± 4 %; p,0.001) and remained lower until mins 11-15 (UnST: 69 ± 6 %; ST: 66 ± 6 %; p=0.776). No further changes occurred throughout the rest of the trial (p<0.040). C SmO2 did not differ at any time between the trials (p=0.263). CONCLUSIONS: This preliminary data suggests a backpack HS has little physiological effect during 30 minutes of walking with a load of 30% the wearers body weight.