Impact of rider position and pedaling cadence on power output and bilateral asymmetry in indoor cycling.

BACKGROUND: This study examines the effects of pedaling cadence and the rider's position on power output and pedaling asymmetry during indoor cycling. METHODS: Participants were 25 male indoor cycling instructors (32.4±4.8 years; 75.7±4.9 kg; 174±4.2 cm) with at least 3 years of cycling experience. In a single session, participants completed 9 training intervals consisting of different combinations of position (standing, sitting), pedaling cadence (75, 100, 120 rpm) and training intensity (75, 80, 85% maximum heart rate, HRmax). RESULTS: During standing intervals, power output was lower (132.4±72.6 W vs. 197.5±53.5 W; P<0.05) and the bilateral leg asymmetry index was greater (52.2±76.6% vs. 12.4±9%; P<0.05) than when subjects pedaled while sitting for a similar work intensity. In contrast, higher power outputs (238.1±46.3 W vs. 153±52.7 W; P<0.05) and lower asymmetry indices (30.4±39.2% vs. 12.6±11%; P<0.05) were recorded in intervals performed at 75 rpm versus 120 rpm despite similar exercise intensities. CONCLUSIONS: Our findings indicate that at similar training intensities, pedaling while standing during indoor cycling generates fewer watts and greater asymmetry than pedaling while sitting. We also observed that a slower pedaling cadence (75 rpm) gives rise to greater generated power and a lower asymmetry index than a faster pedaling cadence (120 rpm).

Influence of the structural components of artificial turf systems on impact attenuation in amateur football players.

The purpose of this research was to evaluate the influence of the structural components of different 3rd generation artificial turf football field systems on the biomechanical response of impact attenuation in amateur football players. A total of 12 amateur football players (24.3 ± 3.7 years, 73.5 ± 5.5 kg, 178.3 ± 4.1 cm and 13.7 ± 4.3 years of sport experience) were evaluated on three third generation artificial turf systems (ATS) with different structural components. ATS were composed of asphalt sub-base and 45 mm of fibre height with (ATS1) and without (ATS2) elastic layer or compacted granular sub-base, 60 mm of fibre height without elastic layer (ATS3). Two triaxial accelerometers were firmly taped to the forehead and the distal end of the right tibia of each individual. The results reveal a higher force reduction on ATS3 in comparison to ATS1 (+6.24%, CI95%: 1.67 to 10.92, ES: 1.07; p < 0.05) and ATS2 (+21.08%, CI95%: 16.51 to 25.66, ES: 2.98; p < 0.05) elastic layer. Tibia acceleration rate was lower on ATS3 than ATS1 (-0.32, CI95%: -0.60 to -0.03, ES: 4.23; p < 0.05) and ATS2 (-0.35, CI95%: -0.64 to -0.06; ES: 4.69; p < 0.05) at 3.3 m/s. A very large correlation (r = 0.7 to 0.9; p < 0.05) was found between energy restitution and fibre height in both head and tibial peak acceleration and stride time. In conclusion, structural components (fibre height, infill, sub-base and elastic layer) determine the mechanical properties of artificial turf fields. A higher force reduction and lower energy restitution diminished the impact received by the player which could protect against injuries associated with impacts compared to harder artificial turf surfaces.

Game Responses During Young Padel Match Play: Age and Sex Comparisons.

García-Benítez, S, Courel-Ibáñez, J, Pérez-Bilbao, T, and Felipe, JL. Game responses during young padel match play: age and sex comparisons. J Strength Cond Res 32(4): 1144-1149, 2018-The purpose of this study was to assess match activity profile and temporal structure in U-16 and U-18 male and female padel players from the 2014 Spanish Youth National Championship. A total of 1,670 rallies from 12 matches were recorded through systematic observation. Variables pertaining to game and point duration, rest interval time, number of strokes per rally (SR), and match total duration were registered. Current findings show that significant influences of age and sex on game demands in youth padel players strengthen the importance of knowing specific game characteristics during formative stages for training accordingly. In particular, padel match activity in youth players was characterized by longer rallies, longer resting interval time, and more number of SR compared with other racket sports, resulting in lower effort index. More specifically, results revealed an increment on match requirements in U-18 players compared with U-16. Besides, we found a greater use of lobs in females, particularly in U-16 players. This information may constitute a useful guide for the design of appropriate game strategies and specific-training sessions according to competitive demands in youth padel players.

Physical and Physiological Responses of Amateur Football Players on Third-Generation Artificial Turf Systems During Simulated Game Situations.

Sánchez-Sánchez, J, García-Unanue, J, Felipe, JL, Jiménez-Reyes, P, Viejo-Romero, D, Gómez-López, M, Hernando, E, Burillo, P, and Gallardo, L. Physical and physiological responses of amateur football players on third generation artificial turf systems during simulated game situations. J Strength Cond Res 30(11): 3165-3177, 2016-The aim of this study is to evaluate the physical and physiological load imposed on amateur football players in a simulated game situation on different artificial turf systems. For that purpose, 20 football players (21.65 ± 3.10 year old) were monitored with Global Positioning Systems and heart rate bands during 45-minutes games on 4 selected artificial turf systems. The results show more covered distance in high-intensity ranges on the system with lower levels of damping and higher rates of rotational traction (p ≤ 0.05). Likewise, this system of artificial turf demonstrated a high number of sprints (12.65 ± 5.67) and more elevated maximum speed peaks during the last part of the game (28.16 ± 2.90 km·h) in contrast to the systems with better damping capacity (p ≤ 0.05). On the other hand, the physiological load was similar across the 4 artificial turf systems (p > 0.05). Finally, the regression analysis demonstrated a significant influence of the mechanical properties of the surface on global distance (15.4%), number (12.6%), and maximum speed (16.6%) of the sprints. To conclude, the mechanical variability of the artificial turf systems resulted in differences in the activity profiles and the players' perceptions during simulated football games.