Concurrent heart rate validity of wearable technology devices during trail running.

Validation of heart rate responses in wearable technology devices is generally composed of laboratory-based protocols that are steady state in nature and as a result, high accuracy measures are returned. However, there is a need to understand device validity in applied settings that include varied intensities of exercise. The purpose was to determine concurrent heart rate validity during trail running. Twenty-one healthy participants volunteered (female n = 10, [mean (SD)]: age = 31 [11] years, height = 173.0 [7] cm, mass = 75.6 [13] kg). Participants were outfitted with wearable technology devices (Garmin Fenix 5 wristwatch, Jabra Elite Sport earbuds, Motiv ring, Scosche Rhythm+ forearm band, Suunto Spartan Sport watch with accompanying chest strap) and completed a self-paced 3.22 km trail run while concurrently wearing a criterion heart rate strap (Polar H7 heart rate monitor). The trail runs were out-and-back with the first 1.61 km in an uphill direction, and the 1.61 return being downhill in nature. Validity was determined through three methods: Mean Absolute Percent Error (MAPE), Bland-Altman Limits of Agreement (LOA), and Lin's Concordance Coefficient (rC). Validity measures overall are as follows: Garmin Fenix 5 (MAPE = 13%, LOA = -32 to 162, rC = 0.32), Jabra Elite Sport (MAPE = 23%, LOA = -464 to 503, rC = 0.38), Motiv ring (MAPE = 16%, LOA = -52 to 96, rC = 0.29), Scosche Rhythm+ (MAPE = 6%, LOA = -114 to 120, rC = 0.79), Suunto Spartan Sport (MAPE = 2%, LOA = -62 to 61, rC = 0.96). All photoplethysmography-based (PPG) devices displayed poor heart rate agreement during variable intensity trail running. Until technological advances occur in PPG-based devices allowing for acceptable agreement, heart rate in outdoor environments should be obtained using an ECG-based chest strap that can be connected to a wristwatch or other comparable receiver.

Caffeine's Effects on an Upper-Body Resistance Exercise Workout.

Salatto, RW, Arevalo, JA, Brown, LE, Wiersma, LD, and Coburn, JW. Caffeine's effects on an upper-body resistance exercise workout. J Strength Cond Res 34(6): 1643-1648, 2020-The purpose of this study was to examine the effects of caffeine on an upper-body resistance exercise workout. Fifteen men (mean ± SD: age, 23.1 ± 1.9 years; body mass, 89.1 ± 13.9 kg; height, 175 ± 6.1 cm) volunteered to come to the laboratory 3 times. During visit 1, 1-repetition maximum (RM) values were determined for the barbell bench press, incline barbell bench press, and dumbbell bench press exercises. For visit 2, subjects consumed either 800-mg caffeine or a placebo. Subjects then completed 3 sets to failure of each exercise using 80% of their 1RM. Visit 3 was the same as visit 2; however, participants consumed the opposite treatment as visit 2. Various perceptual measures were recorded before, during, and after the workouts. The results indicated that participants completed significantly more repetitions per set for the barbell bench press (4.80 ± 2.66) and incline barbell bench press (4.91 ± 2.29) in the caffeine condition compared with the placebo condition (4.42 ± 2.56 and 4.36 ± 2.11, respectively). Higher arousal scores were found in the caffeine condition. For vigor, participants reported higher scores with caffeine before warming up (caffeine = 10.20 ± 4.11, placebo = 6.20 ± 3.23) and mid workout (caffeine = 13.53 ± 2.29, placebo = 11.13 ± 2.79). These results suggest that caffeine has an ergogenic effect on strength workout performance due, at least in part, to positive effects on workout perception. Athletes and recreational lifters may want to consider the ingestion of caffeine before a resistance exercise workout.