Background The range of benefits associated with regular physical activity participation is irrefutable. Despite the well-known benefits, physical inactivity remains one of the major contributing factors to ill-health throughout industrialized countries. Traditional lifestyle interventions such as group education or telephone counseling are effective at increasing physical activity participation; however, physical activity levels tend to decline over time. Consumer-based wearable activity trackers that allow users to objectively monitor activity levels are now widely available and may offer an alternative method for assisting individuals to remain physically active. Objective This review aimed to determine the effects of interventions utilizing consumer-based wearable activity trackers on physical activity participation and sedentary behavior when compared with interventions that do not utilize activity tracker feedback. Methods A systematic review was performed searching the following databases for studies that included the use of a consumer-based wearable activity tracker to improve physical activity participation: Cochrane Controlled Register of Trials, MEDLINE, PubMed, Scopus, Web of Science, Cumulative Index of Nursing and Allied Health Literature, SPORTDiscus, and Health Technology Assessments. Controlled trials of adults comparing the use of a consumer-based wearable activity tracker with other nonactivity tracker–based interventions were included. The main outcome measures were physical activity participation and sedentary behavior. All studies were assessed for risk of bias, and the Grades of Recommendation, Assessment, Development, and Evaluation system was used to rank the quality of evidence. The guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement were followed. A random-effects meta-analysis was completed on the included outcome measures to estimate the treatment effect of interventions that included an activity tracker compared with a control group. Results There was a significant increase in daily step count (standardized mean difference [SMD] 0.24; 95% CI 0.16 to 0.33; P <.001), moderate and vigorous physical activity (SMD 0.27; 95% CI 0.15 to 0.39; P <.001), and energy expenditure (SMD 0.28; 95% CI 0.03 to 0.54; P =.03) and a nonsignificant decrease in sedentary behavior (SMD −0.20; 95% CI −0.43 to 0.03; P =.08) following the intervention versus control comparator across all studies in the meta-analyses. In general, included studies were at low risk of bias, except for performance bias. Heterogeneity varied across the included meta-analyses ranging from low (I 2 =3%) for daily step count through to high (I 2 =67%) for sedentary behavior. Conclusions Utilizing a con...

Compared with cold water, ice slurry ingestion lowered preexercise rectal temperature, increased submaximal endurance running time in the heat (+19% ± 6%), and allowed rectal temperature to become higher at exhaustion. As such, ice slurry ingestion may be an effective and practical precooling maneuver for athletes competing in hot environments.

The purpose of this study was to compare the effects of pre-exercise ice slurry ingestion and cold water immersion on submaximal running time in the heat. On three separate occasions, eight males ran to exhaustion at their first ventilatory threshold in the heat (34.0 ± 0.1 ° C, 52 ± 3% relative humidity) following one of three 30 min pre-exercise manoeuvres: (1) ice slurry ingestion; (2) cold water immersion; or (3) warm fluid ingestion (control). Running time was longer following cold water immersion (56.8 ± 5.6 min; P = 0.008) and ice slurry ingestion (52.7 ± 8.4 min; P = 0.005) compared with control (46.7 ± 7.2 min), but not significantly different between cold water immersion and ice slurry ingestion (P = 0.335). During exercise, rectal temperature was lower with cold water immersion from 15 and 20 min into exercise compared with control and ice slurry ingestion, respectively, and remained lower until 40 min (P = 0.001). At exhaustion rectal temperature was significantly higher following ice slurry ingestion (39.76 ± 0.36 ° C) compared with control (39.48 ± 0.36 ° C; P = 0.042) and tended to be higher than cold water immersion (39.48 ± 0.34 ° C; P = 0.065). As run times were similar between conditions, ice slurry ingestion may be a comparable form of pre-cooling to cold water immersion.

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When well-trained cyclists performed a 25 km cycling time trial under ecologically valid conditions and were blinded to their hydration status, performance, physiological and perceptual variables were not different between trials. These data do not support the residing basis behind many of the current hydration guidelines.