Calf muscle abilities are related to sprint performance in male Rugby Union players

Objectives: To examine the strength of the relationship between plantarflexor power and strength-endurance metrics and 10-m sprint times in male Rugby Union players. A secondary aim was to examine the strength of the relationship within calf muscle metrics. Design: Observational cross-sectional correlational. Setting: Field-based. Participants: Sixteen male Rugby Union players in the National Provincial Championship. Main outcome measures: Participants completed three single-leg calf muscle tests: bodyweight power, weighted power, and strength-endurance. Data were recorded using the Calf Raise application. Three-to-four days later, average and best 10-m sprint performances were collected using timing lights. Results: There were large significant correlations between 10-m sprint performances (average and best times) and calf muscle power (weighted) and strength-endurance (total displacement and work) metrics (r = −0.503 to −0.628). There were large significant correlations between bodyweight and weighted power, weighted power and strength-endurance (total displacement and work), and most strength-endurance metrics (r = 0.520 to 0.943). Conclusions: Our findings emphasise the importance of triceps surae muscle power and strength-endurance for maximal-effort accelerations and sprint performances in Rugby Union. Our data indicate that weighted power and total work from strength-endurance tests are the most useful metrics for further investigation in the context of short sprints and acceleration

Acute sensory and motor response to 45-s heavy isometric holds for the plantar flexors in patients with Achilles tendinopathy

Purpose The purpose of this study was to explore the immediate effects of heavy isometric plantar flexor exercise on sensory output (pain during a functional task and mechanical pain sensitivity) and motor output (plantar flexor torque) in individuals with Achilles tendinopathy. Methods Sixteen subjects with Achilles tendinopathy participated in the study, mean (SD) age 48.6 (8.9) years and Victorian institute assessment-Achilles (VISA-A) score 61.3 (23.0). Sensory testing assessing pain during a functional task, mechanical pain sensitivity and motor output, and plantar flexor peak torque was completed prior to the intervention. All subjects completed a 45-s heavy isometric plantar flexor contraction and were then re-tested using the same sensory and motor tests. Motor output was assessed using isokinetic dynamometry at speeds previously identified as of interest in subjects with Achilles tendinopathy. Results Only 9 of the 16 subjects experienced pain during a functional task, self-reported pain was 4.2 (1.9) numerical rating scale (NRS) pre-intervention and 4.9 (3.2) NRS postintervention (n.s.). Mechanical pressure sensitivity was 446.5 (± 248.5) g/mm2 pre-intervention and 411.8 (± 211.8) g/mm2 post-intervention (n.s.). Mean concentric plantar flexor torque at 90 and 225°/s was 47.1 (14.5) and 33.6 (11.6) Nm, respectively, pre-intervention and 53.0 (18.5) and 33.4 (6.6) Nm post-intervention (p = 0.039 and n.s.). Eccentric torque at 90°/s was 98.5 (34.2) Nm preintervention versus 106.0 (41.4) Nm post-intervention (n.s.). Conclusion In this exploratory study, patients with Achilles tendinopathy had a varied sensory and motor output response to heavy isometric contractions. Using the recommended approach of heavy 45-s isometric contractions did not offer a meaningful acute benefit for sensory or motor output for subjects with Achilles tendinopathy. Based on this study, heavy 45-s isometric contractions cannot be recommended for immediate pain relief or improved motor output for patients with Achilles tendinopathy. Level of evidence IV, prospective cohort study