Monitoring recovery from muscle damage in Rugby Union

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Author
Dodge, Sam
Date
2016Type
Thesis
Publisher
Cardiff Metropolitan University
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INTRODUCTION Acute and long-term decreases in athletic performance as a result
of muscle damage from participating in rugby union, are well documented. To date,
research designed to measure recovery from muscle damage using jump
performance has adopted a wide range of methodologies, often in experimental
settings. The purpose of this study was to investigate performance decrements of
rugby union players in a variety of jump activities after experiencing muscle damage
in an experimental (study 1) and applied (study 2) environment. METHODS In both
studies subjects recorded a baseline squat jump (SJ), countermovement jump
(CMJ), drop jump from 30cm (DJ) and submaximal hop (SH) during which the force
(F), power (P), velocity (V), ground contact time (tc) and flight time (tf) were
measured alongside baseline creatine kinase (CK) levels. Peak force, peak power
output, leg stiffness, reactive strength index (RSI), peak velocity and jump height
were recorded for each of the given jumps. All jumps were then retested 4min, 1d,
2d, 3d and 7d post a stimulus designed to cause muscle damage with CK recorded
at all intervals excluding the 4min interval. In study one subjects completed five sets
of ten repetitions of the lowering portion of a back squat at 95% of their back squat 1-
RM with a five second eccentric contraction. In study two subjects participated in a
full competitive rugby union match. In both studies jump variables were analysed
using separate single-factor repeated-measures analyses of variance and correlation
analysis between CK and jump variables was carried out using a Pearson’s
correlation. The effect size of the change between intervals was also recorded for
each variable measured. RESULTS In study one, a very large (ES = 3.53) increase
in CK was recorded from 256+158 U/I to 813.8+577 U/I, which although not
significant (p>0.05), remained elevated until returning to below baseline levels at 7d
post intervention. All jump activities experienced significant decreases in
performance (p<0.05) across various intervals with DJ RSI displaying the highest
correlation with changes in CK over the seven-day period (r=-.61, p<0.01). In study
two a very large, but non-significant (p>0.05, ES = 1.93) peak from baseline CK
(257.9+91.2 U/I) was recorded at 24hrs post-competition (434+207.8 U/I), which
remained elevated before returning to below baseline levels 7d post competition. No
jump activities experienced significant decreases in performance. CONCLUSION
The results suggest that while jump activities can be used to identify the state of recovery from muscle damage, particularly the RSI of a 30cm DJ, this is dependent
on the stimulus used to instigate muscle damage. It can also be concluded that
results obtained from an experimental setting may not be applicable to an applied
‘real world’ environment. Strength and conditioning practitioners therefore must
assess whether or not the chosen jump method is suitable to the mechanism of
muscle damage experienced by their athletes before implementing a monitoring
programme using athletic performance measures.
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MPhil Thesis
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