Adiposity and grip strength as long-term predictors of objectively measured physical activity in 93 015 adults: the UK Biobank study

BACKGROUND/OBJECTIVES: Fatness and fitness are associated with physical activity (PA) but less is known about the prospective associations of adiposity and muscle strength with PA. This study aimed to determine longitudinal associations of body mass index (BMI), waist circumference (WC) and grip strength (GS) with objectively measured PA. SUBJECTS/METHODS: Data are from the UK Biobank study. At baseline (2006-2010), BMI, WC and GS were objectively measured. At follow-up (2013-2015), a sub-sample of 93 015 participants (52 161 women) wore a tri-axial accelerometer on the dominant wrist for 7 days. Linear regression was performed to investigate longitudinal associations of standardised BMI, WC and GS at baseline with moderate-to-vigorous PA (MVPA) and acceleration after a median 5.7-years follow-up (interquartile range: 4.9-6.5 years). RESULTS: Linear regression revealed strong inverse associations for BMI and WC, and positive associations for GS with follow-up PA; in women, MVPA ranges from lowest to highest quintiles of GS were 42-48 min day(-1) in severely obese (BMI⩾35 kg m(-)(2)), 52-57 min day(-1) in obese (30⩽BMI<35 kg m(-)(2)), 61-65 min day(-1) in overweight (25⩽BMI<30 kg m(-)(2)) and 69-75 min day(-1) in normal weight (18.5⩽BMI<25 kg m(-2)). Follow-up MVPA was also lower in the lowest GS quintile (42-69 min day(-1)) compared with the highest GS quintile (48-75 min day(-1)) across BMI categories in women. The pattern of these associations was generally consistent for men, and in analyses using WC and mean acceleration as exposure and outcome, respectively. CONCLUSIONS: More pronounced obesity and poor strength at baseline independently predict lower activity levels at follow-up. Interventions and policies should aim to improve body composition and muscle strength to promote active living.International Journal of Obesity advance online publication, 6 June 2017; doi:10.1038/ijo.2017.122.This work was supported by the UK Medical Research Council (MC_UU_12015/3), a PhD studentship from MedImmune (to TW), and an Intermediate Basic Science Research Fellowship of British Heart Foundation (FS/12/58/29709 to KW). No financial disclosures were reported by the authors of this paper. This research has been conducted using the UK Biobank Resource under Application Numbers 262 and 12885

ACCURACY OF A WRIST-WORN ACTIVITY MONITOR DURING RESISTANCE TRAINING EXERCISES AT DIFFERENT MOVEMENT SPEEDS

O. Anderson1, A.H.K. Montoye, FACSM2, D. Boss2, J.A. Steeves3, and S.A. Conger1 1Boise State University, Boise, ID;2Alma College, Alma, MI; 3Maryville College, Maryville, TN Speed of movement can affect the accuracy of objective physical activity (PA) monitors. It is likely that speed of movement could affect the accuracy of accelerometer-based PA monitors during other types of exercise. PURPOSE: To assess the ability of the Atlas Wearables Wristband2, an accelerometer-based PA monitor developed specifically for resistance training (RT), to identify the individual RT exercise type and count repetitions during RT exercises at various movement speeds. METHODS: Male and female participants (n=50) aged 18-55 yrs were recruited for this study. Each participant wore an Atlas Wearables Wristband2 on his/her left wrist. Participants completed seven sets of ten repetitions for five different upper/lower body RT exercises (barbell bench press, dumbbell (DB) bent-over row, DB calf raise, DB overhead triceps extension, and DB bicep curl) using a self-selected, light weight. The speed of each set was randomized and completed at a different metronome-paced cadence ranging from a slow cadence of 4 s/rep to a fast cadence of 1 s/rep (sets differed by 0.5 s/rep increments). Percentage of correct activity type identification and repetition counting were calculated. In addition, mean absolute percent error (MAPE) and bias were calculated for repletion counting. One-way ANOVAs were used to compare the actual exercise type/number of repetitions between the seven different speeds. RESULTS: For each exercise, there tended to be significant difference between the slower speeds and the fastest speed for activity type identification and repletion counting (p\u3c0.05). Overall across all exercises, the highest accuracy for activity type identification and repetition counting and the lowest MAPE and bias occurred during the 1.5 s/rep speed (the second fastest speed tested).CONCLUSION: The accuracy of the Atlas Wearables Wristband2 to identify exercise type and count repetitions varied based on the speed of movement during RT exercises. Overall, the exercise type and repetition count accuracy tended to improve as the speed of movement increased up to 1.5 s/rep. The results of this study suggest that researchers using this device should train participants to complete prescribed exercises at specific speeds for the highest accuracy in identifying exercise and counting repetitions during RT exercise

INTER-MONITOR RELIABILITY OF A WRIST-WORN ACTIVITY MONITOR DURING RESISTANCE TRAINING EXERCISES

A.K. Fox1, A.H.K. Montoye, FACSM2, J.A. Steeves3, J.R. Mitrzyk2, C. Beach3, S.A. Conger1 1Boise State University, Boise, ID;2Alma College, Alma, MI; 3Maryville College, Maryville, TN Resistance training (RT) is an important part of the 2018 Physical Activity Guidelines for Americans. Until recently, methods to objectively assess RT exercises have been limited. The Atlas Wearables Wristband2 is an accelerometer-based activity monitor that is capable of identifying individual RT exercises and detecting the number of repetitions, but its inter-monitor reliability has not been investigated. PURPOSE: To determine the inter-monitor reliability of the Atlas Wearables Wristband2 monitor for exercise type identification and repetition counting and to assess the impact that various participant characteristics may have on the inter-monitor reliability. METHODS: Male and female participants (n=62) aged 18-55 yrs were recruited for this study. Each participant wore two Atlas monitors on the left wrist and performed 12 repetitions of 14 different resistance training (including dumbbell, machine, and body weight) exercises using self-selected weight. Inter-monitor reliability was assessed by calculating the percent agreement for each exercise type and for number of repetitions measured between both monitors. Sub-analyses were also completed for reliability by gender, RT experience, and height. Percent agreement and mean absolute percent error were calculated for each activity. Independent t-tests were conducted to assess subgroup comparisons. RESULTS: Overall, the inter-monitor reliability between the two monitors was 80.4±1.3% agreement for exercise type and 59.6±2.2% agreement for number of repetitions. Mean absolute percent errors for repetition counting were low (\u3c1.5 reps) for all 14 exercises. Overall, there were no significant differences in exercise type identification or repetition counting when the data were assessed by gender, RT experience, or height. CONCLUSION: The inter-monitor reliability of the Atlas Wearables Wristband2 was high for exercise type agreement. However, the agreement between monitors when measuring repetitions was slightly lower. The lack of differences in reliability by gender, RT experience, height is encouraging as it suggests similar device reliability across different populations