The influence of surface and speed on biomechanical external loads obtained from wearable devices in rearfoot strike runners

External load variables such as peak tibial acceleration (PTA), peak vertical ground reaction forces (GRF) and its instantaneous vertical loading rate (IVLR) may contribute to running injuries although evidence is conflicting given the influence of training load and tissue health on injuries. These variables are influenced by footwear, speed, surface and foot strike pattern during running. The purpose of this study was to assess the influence of four surfaces and two running speeds on external load variables in rearfoot strike (RFS) runners. Twelve RFS runners (confirmed with sagittal foot contact angle) completed a 2-min running bout on a treadmill and 50-m running bouts over the three surfaces (pavement, rubber track and grass) in standardised shoes at their preferred speed and 20% faster. PTA and vertical GRFs were collected using inertial measurement units and in-shoe force insoles. No interaction or surface effects were observed (p \u3e 0.017). The faster speed produced greater axial PTA (+19.2%; p \u3c 0.001), resultant PTA (+20.7%; p \u3c 0.001), peak vertical GRF (+6.6%; p = 0.002) and IVLR (+16.5%; p \u3c 0.001). These findings suggest that surface type does not influence PTA, peak vertical GRF and IVLR but that running faster increases the magnitude of these external loads regardless of surface type in RFS runners

Potato Ingestion as an Effective Race Fuel Alternative to Improve Cycling Performance in Trained Cyclists

Carbohydrate (CHO) ingestion is an established strategy to improve endurance performance. Race fuels should not only sustain performance, but also be readily digested and absorbed and replenish electrolytes. Potatoes are a cost-effective option that fulfills these criteria; however, their impact on endurance performance remains unexamined. PURPOSE: Compare the effects of potato purée (POT) ingestion during endurance cycling on subsequent performance versus commercial CHO gel (GEL) or a control (water, CTL). METHODS: Twelve trained cyclists (31±9y; 71±8kg; VO2max: 61±9mL/kg/min) consumed a standardized breakfast then performed a 2h cycling challenge (60-85%VO2max) followed by a time trial (6kJ/kg body mass) while consuming POT, GEL, or CTL in a randomized-crossover design. POT, GEL and CTL were administered with U-[13C6]glucose for an indirect estimate of gastric emptying rate. Repeated blood samples were collected. RESULTS: Time trial performance significantly improved (P=0.03) with POT (33.0±4.5min) and GEL (33.0±4.2min) versus CTL condition (39.5±7.9min); while POT and GEL conditions (P=1.00) had no difference. Post-challenge, blood glucose concentrations were lower (P0.05). CONCLUSION: Potatoes served as a viable alternative to commercial gels by sustaining performance and blood glucose concentrations during endurance cycling events in trained cyclists