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Recently, a commercially available starting 'ledge' designed to reduce foot slippage during the execution of the backstroke start was introduced in competitive swimming. For the purpose of identifying potential safety consequences, the present study investigated the effect of ledge use on head depths, speeds, and distances in backstroke starts of athletes with no prior or only novice familiarity of the ledge. Competitive backstroke starts were performed with and without ledges by high school-aged (14.5 to 19.2 yr, N = 61) swimmers in 1.52 m of water during a closed testing session. A SIMI Reality Motion System in a calibrated space using three cameras was employed for filming starts. Dependent measures were initia l head height (Yset), distance from wall at entry (Xentry), entry angle (Angleentry), horizontal velocity at head entry (XVelentry), resultant velocity at entry (ResVelentry), maximum depth of the center of the head (Ymhd), resultant velocity at maximum head depth (ResVelmhd), and distance from the wall at maximum head depth (Xmhd). The ledge (L) condition showed significant increases compared to the non-ledge (NL) condition in Xentry (L 1.61 ± 0.59 m, NL 1.50 ± 0.53 m, p < .001), ResVelentry (L 3.44 ± 0.97 m·s -1 , NL 3.08 ± 1.00 m·s -1 , p < .001), Angleentry (L 43.13 ± 16.97, NL 39.66 ± 18.11, p = .030), Xmhd (L 4.18 ± 0.58 m, NL 4.09 ± 0.63 m, p = .008), and Ymhd (L 0.54 ± 0.21 m, NL 0.49 ± 0.18, p <.001). Backstroke starts using the ledge modestly affected 5 of 8 dependent measures in a direction arguably associated with an increased risk to the novice swimmer.

This study aimed to characterize and describe finishing time trends of the fastest 100 performers in the men's and women's marathon, halfmarathon, and road 10-km each year from 2001 to 2019 and assess the underlying basis for recent performance improvements. Methods: The top 100 performers for each sex, event, and year were partitioned into four arbitrary ranking groups: 1-10, 11-25, 26-50, and 51-100. The percent improvement in mean performance time for each year beyond 2001 was calculated for each ranking group, event, and sex. Multiple linear regression was also used to determine improvement trend for each ranking group, both sexes, and all events for each 3-yr period between Olympic years. Results: In total, 11,400 performances in the marathon, half-marathon, and 10-km road races from 2001 to 2019 were analyzed. The 3-yr period preceding the original date of the Tokyo Olympics (2017-2019) accounted for 44% and 35% of the overall improvement in marathon time from 2001 to 2019 for women and men, respectively. The years 2017-2019 featured the largest average improvement of any 3-yr period and was the only period where nearly every ranking group in every event for both sexes improved. Conclusions: The results suggest that recent world record performances are a result of overall circumstances affecting road racing (e.g., shoe technology) rather than the outstanding physiology of individual top runners, per se.

Listening to music while exercising can alter afferent feedback from breathing sounds; however, it is currently unknown whether auditory distraction with music mitigates exertional dyspnea in healthy individuals. Purpose: This study aimed to determine whether listening to music through headphones (a) affects the sensory (breathing intensity [BI]) and/or affective (breathing unpleasantness [BU]) components of dyspnea during exercise at different intensities and (b) affects exercise performance. Methods: Twenty-two recreationally active individuals (24 ± 3 yr, 10 women) performed two 5-min constant loads (10% below/above gas exchange threshold [GET]) and an 8-km cycling time trial with ambient laboratory noise or self-selected music in a randomized crossover design. BI, BU, and ventilation ( VE ) were measured at each minute of the constant loads and every 2 km of the time trial. Ratios of BU/ VE and BI/ VE were used to examine the gain in dyspnea during the time trial. Results: In the 10% below GET trial, BU was reduced in the first (P = 0.03) and final (P = 0.04) minutes. In the 10% above GET trial, BU and BI were reduced with music (P < 0.05). During the time trial with music, BU/ VE was significantly attenuated by 9%-13% (P < 0.05) despite a greater heart rate and self-selected power output (P < 0.05). Conclusions: Music through headphones mitigated the sensation of dyspnea and changed the accretion of dyspnea per unit increase in VE leading to a higher self-selected workload during self-paced exercise. The dyspnea-reducing intervention of self-selected music may improve exercise tolerance and performance and promote adherence to regular aerobic exercise.

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