Heart rate processing algorithms and exercise duration on reliability and validity decisions in biceps-worn Polar Verity Sense and OH1 wearables.

Consumer wearable technology use is widespread and there is a need to validate measures obtained in uncontrolled settings. Because no standard exists for the treatment of heart rate data during exercise, the effect of different approaches on reliability (Coefficient of Variation [CV], Intraclass Correlation Coefficient [ICC]) and validity (Mean Absolute Percent Error [MAPE], Lin's Concordance Correlation Coefficient [CCC)] were determined in the Polar Verity Sense and OH1 during trail running. The Verity Sense met the reliability (CV < 5%, ICC > 0.7) and validity thresholds (MAPE < 5%, CCC > 0.9) in all cases. The OH1 met reliability thresholds in all cases except entire session average (ICC = 0.57). The OH1 met the validity MAPE threshold in all cases (3.3-4.1%), but not CCC (0.6-0.86). Despite various heart rate data processing methods, the approach may not affect reliability and validity interpretation provided adequate data points are obtained. It is also possible that a large volume of data will artificially inflate metrics.

Tennis forehand kinematics change as post-impact ball speed is altered.

Peak joint angles and joint angular velocities were evaluated for varying speed forehands in an attempt to better understand what kinematic variables are most closely related to increases in post-impact ball velocity above 50% of maximal effort. High-speed video was used to measure three-dimensional motion for 12 highly skilled tennis players who performed forehands at three different post-impact ball speeds: fast (42.7 +/- 3.8 m/s), medium (32.1 +/- 2.9 m/s), and slow (21.4 +/- 2.0 m/s). Several dominant-side peak joint angles (prior to ball impact) increased as post-impact ball speed increased from slow to fast: wrist extension (16%), trunk rotation (28%), hip flexion (38%), knee flexion (27%), and dorsiflexion (5%). Between the aforementioned peak joint angles and ball impact, dominant-side peak angular velocities increased as ball speed increased from slow to fast: peak wrist flexion (118%), elbow flexion (176%), trunk rotation (99%), hip extension (143%), knee extension (56%), and plantarflexion (87%). Most kinematic variables changed as forehand ball speed changed; however, some variables changed more than others, indicating that range of motion and angular velocity for some joints may be more closely related to post-impact ball speed than for other joints.

Metabolic energy expenditure during spring-loaded crutch ambulation.

CONTEXT: Individuals using traditional axillary crutches to ambulate expend approximately twice as much energy as individuals who perform able-bodied gait. A relatively novel spring-loaded crutch now being marketed may reduce metabolic energy expenditure during crutch ambulation. This idea, however, had not yet been tested. OBJECTIVE: To determine whether the novel spring-loaded crutch reduces oxygen consumption during crutch ambulation, relative to traditional-crutch ambulation. A secondary purpose was to evaluate the design for subject-perceived comfort and ease of use. DESIGN: Within-subject. SETTING: Indoor track. PARTICIPANTS: 10 able-bodied men and 10 able-bodied women. INTERVENTIONS: The independent variable was crutch design. Each subject ambulated using 3 different crutch designs (traditional, spring-loaded, and modified spring-loaded), in a randomized order. MAIN OUTCOME MEASURES: The primary dependent variable was oxygen consumption. Secondary dependent variables were subject-perceived comfort and ease of use, as rated by the subjects using a 100-mm visual analog scale. Dependent variables were compared among the 3 crutch designs using a 1-way repeated-measures ANOVA (α = .05). RESULTS: Oxygen consumption during spring-loaded-crutch ambulation (17.88 ± 2.13 mL · kg⁻¹ · min⁻¹) was 6.2% greater (P = .015; effect size [ES] = .50) than during traditional axillary-crutch ambulation (16.84 ± 2.08 mL · kg⁻¹ · min⁻¹). There was no statistically significant difference (P = .068; ES = -.45) for oxygen consumption between spring-loaded-crutch ambulation and ambulation using the modified crutch (17.03 ± 1.61 mL · kg⁻¹ · min⁻¹). Subjects perceived the spring-loaded crutch to be more comfortable (P < .001; ES = .56) than the traditional crutch. There was no difference (P = .159; ES = -.09) between the spring-loaded and traditional crutches for subject-perceived ease of use. CONCLUSIONS: Compared with traditional axillary crutches, the novel spring-loaded crutch may be more comfortable but does not appear to benefit subjects via reduced metabolic energy expenditure.

Weight loss and weight gain among participants in a community-based weight loss Challenge.

BACKGROUND: To describe the characteristics of participants who registered for multiple annual offerings of a community-based weight loss program called The Challenge, and to determine participant characteristics associated with weight change over multiple offerings of The Challenge occurring during the years 2010-2016. METHODS: Multivariable linear mixed effects analyses were conducted to describe percent weight change within and between offerings of The Challenge by participant characteristics. RESULTS: There were 669 and 575 participants included in the within and between analyses, respectively, for offerings of The Challenge. Among the 434 participants who lost weight in their first attempt at The Challenge and completed the initial weigh-in for a subsequent offering of The Challenge, 22.4% maintained their weight loss or had greater weight loss by the next Challenge, 40.3% gained back some weight, and 37.3% gained back all or more of the weight they lost during their first Challenge. Men had a significantly greater percent weight loss compared to women in their first and second Challenge and men were more likely to gain weight between Challenges. Participants who returned to more Challenges had a greater accumulated percent weight loss compared to those who returned to fewer Challenges. CONCLUSIONS: The current weight loss Challenge appears to contribute to helping a percentage of participants lose weight and maintain some or all of the weight loss.

Validity of wrist-worn consumer products to measure heart rate and energy expenditure.

INTRODUCTION: The ability to monitor physical activity throughout the day and during various activities continues to improve with the development of wrist-worn monitors. However, the accuracy of wrist-worn monitors to measure both heart rate and energy expenditure during physical activity is still unclear. The purpose of this study was to determine the accuracy of several popular wrist-worn monitors at measuring heart rate and energy expenditure. METHODS: Participants wore the TomTom Cardio, Microsoft Band and Fitbit Surge on randomly assigned locations on each wrist. The maximum number of monitors per wrist was two. The criteria used for heart rate and energy expenditure were a three-lead electrocardiogram and indirect calorimetry using a metabolic cart. Participants exercised on a treadmill at 3.2, 4.8, 6.4, 8 and 9.7 km/h for 3 minutes at each speed, with no rest between speeds. Heart rate and energy expenditure were manually recorded every minute throughout the protocol. RESULTS: Mean absolute percentage error for heart rate varied from 2.17 to 8.06% for the Fitbit Surge, from 1.01 to 7.49% for the TomTom Cardio and from 1.31 to 7.37% for the Microsoft Band. The mean absolute percentage error for energy expenditure varied from 25.4 to 61.8% for the Fitbit Surge, from 0.4 to 26.6% for the TomTom Cardio and from 1.8 to 9.4% for the Microsoft Band. CONCLUSION: Data from these devices may be useful in obtaining an estimate of heart rate for everyday activities and general exercise, but energy expenditure from these devices may be significantly over- or underestimated.

Home-based resistance training for older adults: a systematic review.

Home-based resistance exercise is commonly used for individuals who might not have access or the ability to use traditional resistance exercise. However, the extent to which home-based resistance exercise can improve both strength and functional ability has not been investigated in healthy older individuals using a systematic analysis. The current article systematically reviewed the effectiveness of home-based resistance exercise on strength and functional ability. Search engines included Academic Search Premier, CINAHL, PubMed, PsycINFO, MEDLINE, SPORTDiscus and Web of Science. A total of 649 articles were found using the key words "home-based" and "strength" and "older" or "elderly", with eight articles meeting the final criteria. The average age of the participants was 76 years, with the average duration of exercise training ranging from 8 weeks to 120 weeks. Of the eight studies, a significant increase in knee extension strength was found in five studies. Functional ability significantly improved in seven of the eight studies, with the average decrease in Timed Up & Go test being -0.8 ± 0.5 s. Three studies included greater amounts of supervised visits compared with the other five studies (∼51% vs ∼7%). The more supervised studies had significant increases in strength and functional ability. Overall, home-based resistance exercise can improve both strength and functional ability, but the improvements are generally small. The intensity of the exercises might not progress sufficiently enough to produce large improvements in strength as a result of less supervision or a lack of motivation to increase the intensity further.

Pedometer-based walking interventions for free-living adults with type 2 diabetes: a systematic review.

Physical activity (PA) is prescribed as an important method of treatment for type 2 diabetes (T2DM), but is neglected in a majority of patients. Walking is an appropriate and safe form of PA which improves glucose utilization in inactive people diagnosed with T2DM. Pedometers have been successfully used to motivate and track progress in many types of walking programs, but there is no current review of their effectiveness compared to other methods to increase PA in people with T2DM. A systematic literature review was performed using MEDLINE, CINAHL, SPORTDiscus, ERIC, and Academic Search Premier to determine the effectiveness of pedometer-based walking interventions at increasing PA in free-living adults with T2DM. Ten studies from 2004 to 2011 were included. All studies were randomized controlled trials except for one quasi-experimental design. Interventions lasted from 6 weeks to 6 months and only 2 studies showed significant improvements in blood glucose control following the intervention. Nine of the ten interventions were able to produce an increase in PA using a pedometer and/or other methods. Pedometers are effective means of increasing PA among T2DM patients in the short-term while several other intervention methods beyond normal treatment are also successful. Future research should include longer intervention durations, low cost methods, larger sample sizes, and dietary intervention components to further understand successful intervention techniques for patients with T2DM.