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Effects of six weeks of resistance detraining on strength, sprint ability and ballistic performance in semi-professional rugby union players

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Abstract

The purpose of this investigation was to determine the effects of resistance detraining on strength, sprint ability and ballistic performance in ten semi-professional rugby union players (mean ± SD; age = 20.5 ± 1.4 years; mass = 96.4 ± 6.5 kg; height = 1.85 ± 0.04). Strength, sprint times and ballistic upper and lower body testing sessions were conducted the week prior to, and the week following the resistance detraining. There were trivial to small negative reductions in 1RM bench press (-1.5%; ES = -0.10), 1RM back squat (-6 %; ES = -0.50) and heavy load (60-75% 1RM) peak force (PF) production (-1 to 2%; ES = -0.02 to -0.70). Trivial to small decreases (-2 to -6%; ES = -0.20 to -0.35) in countermovement bench throw (CMBT) maximum peak force (PFmax [-2%]) maximum peak velocity (PVmax [-4%]) and maximum peak power (PPmax [-6%]). There were moderate (ES = 0.75; p = 0.06) and very large (ES = -2.30; p = 0.07) negative shifts in countermovement jump (CMJ) PVmax (-35%) and PPmax (-14%); however a small (ES = 0.43) increase was observed in PFmax (9%). There were also large to very large (ES = 1.10 – 2.30) increases (decrements) in sprint times over 10, 20 and 30 m (2 to 3%). Current strength and CMJ load specific findings suggest that the decay rates using lighter high-velocity loads are greater than that of heavy high-force loads. These finding indicate that a strength/high force training stimulus may not be needed to retain these specific qualities during acute rest periods (e.g. 2 to 4 weeks); conversely high velocity ballistic and sprint training is recommended every five to ten days to help retain these respective qualities during the off-season. Key Words - Off-season, active rest, force, velocity, power, squat, bench press, jump, throw.

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The load that maximizes mechanical power output (Pmax) has received considerable research attention owing to its perceived importance to training prescription. However, it may be that identifying Pmax is of little importance if the difference in power output about Pmax is insubstantial. Additionally, comparing the effect of load on power output between studies is problematic due to various methodological differences. The purpose of this study therefore was to quantify the concentric power output for a machine squat-jump across a spectrum of loads (10-100% of 1 repetition maximum [1RM]). To estimate Pmax load and proximate loads a quadratic was fitted to the power output (Watts) and load (% of 1RM) of 18 well-trained rugby athletes. Pmax for peak and mean power output occurred at 21.6 +/- 7.1% of 1RM (mean +/- SD) and 39.0 +/- 8.6% of 1RM, respectively. A 20% change in load either side of the maximum resulted in a mean decrease of only 9.9% (90% confidence limits +/-2.4%) and 5.4% (+/-0.9%) in peak and mean power respectively; standard deviations about these means (representing individual differences in the decrease) were 6.0% and 2.1%, respectively (90% confidence limits x//1.34). It appears that most athletes have a broad peak in their power profile for peak or mean power. The preoccupation of identifying one load for maximizing power output would seem less meaningful than many practitioners and scientists believe.
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The purpose of the present study was to investigate the effect of short-term resistance training and detraining on shot put throwing performance. Eleven young healthy subjects with basic shot put skills participated in 14 weeks of resistance training, which was followed by 4 weeks of detraining. Shot put performance in four field tests was measured before (T1) and after (T2) resistance training and after detraining (T3). At the same time points, one repetition maximum (1RM) was measured in squat, bench press, and leg press. Fat-free mass (FFM) was determined with dual x-ray absorptiometry and muscle biopsies obtained from vastus lateralis for the determination of fiber type composition and cross-sectional area (CSA). 1RM strength increased 22-34% (p < 0.01) at T2 and decreased 4-5% (not significantly different) at T3. Shot put performance increased 6-12% (p < 0.05) after training and remained unaltered after detraining. FFM increased at T2 (p < 0.05) but remained unchanged between T2 and T3. Muscle fiber CSA increased 12-18% (p < 0.05) at T2. Type I muscle fiber CSA was not altered after detraining, but type IIa and IIx fiber CSA was reduced 10-12% (p < 0.05). The percentage of type IIx muscle fibers was reduced after training (T1 = 18.7 +/- 4, T2 = 10.4 +/- 1; p < 0.05), and it was increased at T3 compared with T2 (T3 = 13.7 +/- 1; p < 0.05). These results suggest that shot put performance remains unaltered after 4 weeks of complete detraining in moderately resistance-trained subjects. This might be linked to the concomitant reduction of muscle fiber CSA and increase in the percentage of type IIx muscle fibers.
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