Abstract
Before major athletic events, a taper is often prescribed to facilitate recovery and enhance performance. However, it is unknown which taper model is most effective for peaking maximal strength and positively augmenting skeletal muscle. Thus, the purpose of this study was to compare performance outcomes and skeletal muscle adaptations following a step vs. an exponential taper in strength athletes. Sixteen powerlifters (24.0 ± 4.0 years, 174.4 ± 8.2 cm, 89.8 ± 21.4 kg) participated in a 6-week training program aimed at peaking maximal strength on back squat [initial 1-repetition-maximum (1RM): 174.7 ± 33.4 kg], bench press (118.5 ± 29.9 kg), and deadlift (189.9 ± 41.2 kg). Powerlifters were matched based on relative maximal strength, and randomly assigned to either (a) 1-week overreach and 1-week step taper or (b) 1-week overreach and 3-week exponential taper. Athletes were tested pre- and post-training on measures of body composition, jumping performance, isometric squat, and 1RM. Whole muscle size was assessed at the proximal, middle, and distal vastus lateralis using ultrasonography and microbiopsies at the middle vastus lateralis site. Muscle samples (n = 15) were analyzed for fiber size, fiber type [myosin-heavy chain (MHC)-I, -IIA, -IIX, hybrid-I/IIA] using whole muscle immunohistochemistry and single fiber dot blots, gene expression, and microRNA abundance. There were significant main time effects for 1RM squat (p < 0.001), bench press (p < 0.001), and deadlift, (p = 0.024), powerlifting total (p < 0.001), Wilks Score (p < 0.001), squat jump peak-power scaled to body mass (p = 0.001), body mass (p = 0.005), fat mass (p = 0.002), and fat mass index (p = 0.002). There were significant main time effects for medial whole muscle cross-sectional area (mCSA) (p = 0.006) and averaged sites (p < 0.001). There was also a significant interaction for MHC-IIA fiber cross-sectional area (fCSA) (p = 0.014) with post hoc comparisons revealing increases following the step-taper only (p = 0.002). There were significant main time effects for single-fiber MHC-I% (p = 0.015) and MHC-IIA% (p = 0.033), as well as for MyoD (p = 0.002), MyoG (p = 0.037), and miR-499a (p = 0.033). Overall, increases in whole mCSA, fCSA, MHC-IIA fCSA, and MHC transitions appeared to favor the step taper group. An overreach followed by a step taper appears to produce a myocellular environment that enhances skeletal muscle adaptations, whereas an exponential taper may favor neuromuscular performance.
Highlights
Before major competitions, a taper is often prescribed as the final stage of training aimed at decreasing physiological and psychological fatigue to achieve optimal preparedness (Mujika and Padilla, 2003; Travis et al, 2020c)
Increases in powerlifting performance following the step and exponential tapers appeared to be mediated by whole muscle, single muscle fiber, and myocellular adaptations
Increases in myosin-heavy chain (MHC)-IIA content with concomitant decreases in MHC-I and -IIX content were observed following the step taper. These myosin isoform shifts toward the MHCIIA phenotype appear to be related to changes in underlying myocellular signaling (i.e., Sox6 up-regulation and miRNA-499a down-regulation) responsible for fiber-type transitions
Summary
A taper is often prescribed as the final stage of training aimed at decreasing physiological and psychological fatigue to achieve optimal preparedness (Mujika and Padilla, 2003; Travis et al, 2020c). Only two studies have experimentally compared tapering strategies aimed at improving maximal strength: (a) +5% vs −10% intensity manipulation with a ∼70% volume-load reduction using a step taper (Pritchard et al, 2019), and (b) a step vs an exponential taper with a ∼54% volume-load reduction while maintaining intensity (Seppänen and Häkkinen, 2020). These data suggest that a higher intensity taper and an exponential taper over 2-weeks may produce favorable outcomes. The manner in which volume-load is reduced (e.g., step-fashion, exponentially decayed) over a 1 or 3-week duration with the aim of peaking maximal strength requires further examination
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