Ricerche Dicembre 2021

In questo articolo riportiamo gli abstract originali di quelli che consideriamo i 4 articoli scientifici di maggior impatto pubblicati nelle riviste di scienze dello sport classificate come SCImago Q1 e Q2 nel mese di Dicembre 2021. Questo è per condividere quelle che secondo noi sono le novità scientifiche più interessanti nell’ambito della preparazione atletica e performance sportiva. Gli articoli proposti sono stati selezionati a seguito di una ricerca condotta su google scholar digitando le seguenti parole chiave: Strength training”, “Resistance training”, “Endurance training”,” Sprint training”, “Aerobic training”, “Anaerobic training”.

• Kipp, K. (2021). Joint and pull phase specific relative effort in weightlifting and simulated training effects. Sports Biomechanics, 1-13.

The purposes of this study were to quantify the relative effort (RE) of the extensor and plantarflexor muscles during the clean and simulate the effects of strength and speed-strength training on joint and pull phase specific RE. Five weightlifters performed the clean at 85% of their one-repetition maximum, while motion capture and ground reaction forces were recorded and used to calculate lower body net joint moments via inverse dynamics (NJM_ID). Joint angle and angular velocity data were used as input to a musculoskeletal model that estimated maximum NJM (NJM_max) weightlifters could theoretically generate. The RE of the hip and knee extensor and ankle plantarflexor muscles were calculated as the ratios between NJM_ID and NJM_max. Model parameters were changed to simulate the effects of strength and speed-strength training. Results show that simulated strength training decreased RE of all muscle groups during the first and second pull. In contrast, speed-strength training decreased hip extensor and knee extensor RE during the first pull and second pull, respectively. Strength training may have broad and consistent effects on RE during the clean, whereas speed-strength training may have more joint and phase-specific effects.

https://doi.org/10.1080/14763141.2021.2019303

• Pakosz, P., Lukanova-Jakubowska, A., Łuszczki, E., Gnoiński, M., & García-García, O. (2021). Asymmetry and changes in the neuromuscular profile of short-track athletes as a result of strength training. Plos one, 16(12), e0261265.

• Vieira, J. G., Sardeli, A. V., Dias, M. R., Campos, Y., Sant’Ana, L., Leitão, L., … & Vianna, J. (2021). Effects of Resistance Training to Muscle Failure on Acute Fatigue: A Systematic Review and Meta-Analysis. Sports Medicine, 1-23.

Background: Proper design of resistance training (RT) variables is a key factor to reach the maximum potential of neuromuscular adaptations. Among those variables, the use of RT performed to failure (RTF) may lead to a different magnitude of acute fatigue compared with RT not performed to failure (RTNF). The fatigue response could interfere with acute adaptive changes, in turn regulating long-term adaptations. Considering that the level of fatigue affects long-term adaptations, it is important to determine how fatigue is affected by RTF versus RTNF. Objective: The aim of this systematic review and meta-analysis was to compare the effects of RTF versus RTNF on acute fatigue. Methods: The search was conducted in January 2021 in seven databases. Only studies with a crossover design that investigated the acute biomechanical properties (vertical jump height, velocity of movement, power output, or isometric strength), metabolic response (lactate or ammonia concentration), muscle damage (creatine kinase activity), and rating of perceived exertion (RPE) were selected. The data (mean ± standard deviation and sample size) were extracted from the included studies and were either converted into the standardized mean difference (SMD) or maintained in the raw mean difference (RMD) when the studies reported the results in the same scale. Random-effects meta-analyses were performed. Results: Twenty studies were included in the systematic review and 12 were included in the meta-analysis. The main meta-analyses indicated greater decrease of biomechanical properties for RTF compared with RTNF (SMD − 0.96, 95% confidence interval [CI] − 1.43 to − 0.49, p < 0.001). Furthermore, there was a larger increase in metabolic response (RMD 4.48 mmol·L⁻¹, 95% CI 3.19–5.78, p < 0.001), muscle damage (SMD 0.76, 95% CI 0.31–1.21, p = 0.001), and RPE (SMD 1.93, 95% CI 0.87–3.00, p < 0.001) for RTF compared with RTNF. Further exploratory subgroup analyses showed that training status (p = 0.92), timepoint (p = 0.89), load (p = 0.10), and volume (p = 0.12) did not affect biomechanical properties; however, greater loss in the movement velocity test occurred on upper limbs compared with lower limbs (p < 0.001). Blood ammonia concentration was greater after RTF than RTNF (RMD 44.66 μmol·L⁻¹, 95% CI 32.27–57.05, p < 0.001), as was 48 h post-exercise blood creatine kinase activity (SMD 0.86, 95% CI 0.33–1.42, p = 0.002). Furthermore, although there was considerable heterogeneity in the overall analysis (I² = 83.72%; p < 0.01), a significant difference in RPE after RTF compared with RTNF was only found for studies that did not equalize training volumes. Conclusions: In summary, RTF compared with RTNF led to a greater decrease in biomechanical properties and a simultaneous increase in metabolic response, higher muscle damage, and RPE. The exploratory analyses suggested a greater impairment in the velocity of movement test for the upper limbs, more pronounced muscle damage 48 h post-exercise, and a greater RPE in studies with non-equalized volume after the RTF session compared with RTNF. Therefore, it can be concluded that RTF leads to greater acute fatigue compared with RTNF. The higher acute fatigue after RTF can also have an important impact on chronic adaptive processes following RT; however, the greater acute fatigue following RTF can extend the time needed for recovery, which should be considered when RTF is used.

https://doi.org/10.1007/s40279-021-01602-x

• Markov, A., Chaabene, H., Hauser, L., Behm, S., Bloch, W., Puta, C., & Granacher, U. (2021). Acute Effects of Aerobic Exercise on Muscle Strength and Power in Trained Male Individuals: A Systematic Review with Meta-analysis. Sports Medicine, 1-14.

Background: Concurrent training can be an effective and time-efficient method to improve both muscle strength and aerobic capacity. A major challenge with concurrent training is how to adequately combine and sequence strength exercise and aerobic exercise to avoid interference effects. This is particularly relevant for athletes. Objective: We aimed to examine the acute effects of aerobic exercise on subsequent measures of muscle strength and power in trained male individuals. Design: We performed a systematic review with meta-analysis. Data Sources: Systematic literature searches in the electronic databases PubMed, Web of Science, and Google Scholar were conducted up to July 2021. Eligibility Criteria: for Selecting Studies: Studies were included that applied a within-group repeated-measures design and examined the acute effects of aerobic exercise (i.e., running, cycling exercise) on subsequent measures of lower limb muscle strength (e.g., maximal isometric force of the knee extensors) and/or proxies of lower limb muscle power (e.g., countermovement jump height) in trained individuals. Results: Fifteen studies met the inclusion criteria. Aerobic exercise resulted in moderate declines in muscle strength (standardized mean difference [SMD] = 0.79; p = 0.003). Low-intensity aerobic exercise did not moderate effects on muscle strength (SMD = 0.65; p = 0.157) while moderate-to-high intensity aerobic exercise resulted in moderate declines in muscle strength (SMD = 0.65; p = 0.020). However, the difference between subgroups was not statistically significant (p = 0.979). Regarding aerobic exercise duration, large declines in muscle strength were found after > 30 min (SMD = 1.02; p = 0.049) while ≤ 30 min of aerobic exercise induced moderate declines in muscle strength (SMD = 0.59; p = 0.013). The subgroup difference was not statistically significant (p = 0.204). Cycling exercise resulted in significantly larger decrements in muscle strength (SMD = 0.79; p = 0.002) compared with running (SMD = 0.28; p = 0.035). The difference between subgroups was statistically significant (p < 0.0001). For muscle power, aerobic exercise did not result in any statistically significant changes (SMD = 0.04; p = 0.846). Conclusions: Aerobic exercise induced moderate declines in measures of muscle strength with no statistically significant effects on proxies of muscle power in trained male individuals. It appears that higher compared with lower intensity as well as longer compared with shorter aerobic exercise duration exacerbate acute declines in muscle strength. Our results provide evidence for acute interference effects when aerobic exercies is performed before strength exercises. These findings may help practitioners to better prescribe single training sessions, particularly if environmental and/or infrastructural reasons (e.g., availability of training facilities) do not allow the application of strength training before aerobic exercise.

https://doi.org/10.1007/s40279-021-01615-6