The Effects of Three Correction Strategies of Errors on the Snatch Technique in 10-12-Year-Old Children: A Randomized Controlled Trial.

ABSTRACT: Souissi, MA, Elghoul, Y, Souissi, H, Masmoudi, L, Ammar, A, Hamdi Chtourou, and Souissi, N. The effects of three corrections strategies of errors on the snatch technique in 10-12-year-old children: A randomized controlled trial. J Strength Cond Res 37(6): 1218-1224, 2023-Sports movement correction is one of the major problems for motor control and learning. Therefore, the purpose of the present study was to determine which of the 3 strategies, i.e., the self-observation method with direct instructions (SO-DI), self-observation alone (SO), or the direct instruction (DI), would be useful for correcting errors during the snatch technique. Forty-eight children with 2 months of experience were randomly assigned to one of 4 training conditions: SO-DI, SO, DI, or control. In this study, the experience lasted 15 sessions. Subjects completed the test sessions before (T 0 ) and after (T 1 ) 12 training sessions and a retention test session after 2 weeks (T 2 ). The Kinovea version 0.8.15 software was used to measure the kinematic parameters of weightlifting performance. After the training intervention, the data showed that the SO-DI group registered a greater improvement in all kinematic parameters compared with the SO, DI, and control groups, and this benefit was present 2 weeks later in the retention test (e.g., the horizontal displacement of the bar in the first pull with respect to the starting position [T1 vs. T0: +32.57 ± 6.69%, d = 1.87, p < 0.001; T2 vs. T0: 25.07 ± 11.55%, d = 1.32, p < 0.001] and the horizontal displacement of the bar between the receiving position and the reference line [T1 vs. T0: 24.34 ± 29%, d = 1.17, p < 0.01; T2 vs. T0: 25.53 ± 30.4%, d = 0.99, p < 0.01]). The results of the present study could have practical implications for physical education teachers because, even if practice is required to improve the technique, the effectiveness of the learning process is essential to enhance learner self-efficacy and motivation.

How Does the Central Nervous System Control Forthcoming Movement with Different Emotional Stimuli?

Maintaining postural balance is a key factor in human motor skills, based in part on emotional stimuli. Our objective in this study was to measure the effect of emotion on postural control as influenced by the direction of forthcoming movement. Eighteen right-handed women initiated a step forward or backward or remained in a static position after visualizing an emotional stimulus (positive, negative, or neutral). Center of pressure (COP) parameters (2D velocity, Medio-lateral (ML), and antero-posterior (AP) amplitude) were recorded for 3-second windows for movement direction and emotional stimulus. We observed a motion * direction effect on 2D velocity, characterized by a decrease in the emotional stimulus and static direction windows. The participants' ML amplitude was influenced by direction, and their reduced amplitude was evident in the presence of emotions. AP amplitude was high in the direction versus emotion window. In the static position, the AP amplitude was high in the direction window and low in the emotion window. The participants' movement planning and programming phase (direction window) was characterized by less oscillation for forward or backward movements and more oscillation before movement, suggesting anticipatory postural adjustments in the emotion window. Static direction was characterized by low oscillation, compared to forward and backward movement and in negative versus positive emotional context, proving the interactive impact of direction and emotion on COP amplitudes. Thus, postural control was influenced by both movement (direction) and emotional content (valence). This study provided insight regarding the interactive effect of emotion and direction on planning and programming forthcoming movement.

Distance Motor Learning during the COVID-19 Induced Confinement: Video Feedback with a Pedagogical Activity Improves the Snatch Technique in Young Athletes.

The purpose of the present study was to investigate which of two strategies, Video Feedback with Pedagogical Activity (VF-PA) or Video Feedback (VF), would be more beneficial for the remote error correction of the snatch weightlifting technique during the confinement period. Thirty-five school aged children with at least three months of weightlifting experience were randomized to one of three training conditions: VF-PA, VF or the Control group (CONT). Subjects underwent test sessions one week before (T0) and one day after (T1) a six-session training period and a retention test session a week later (T2). During each test session, the Kinovea version 0.8.15 software measured the kinematic parameters of the snatch performance. Following distance learning sessions (T1), the VF-PA improved various kinematic parameters (i.e., barbell horizontal displacements, maximum height, looping and symmetry) compared with T0 (p < 0.5; Cohen's d = 0.58-1.1). Most of these improvements were maintained during the retention test (T2) (p<0.01, Cohen's d = 1.2-1.3) when compared withT0. However, the VF group improved only twoparameters (i.e., barbell symmetry and horizontal displacement) at T1 (p < 0.05; Cohen's d = 0.9), which were not maintained at T2. Better horizontal displacement and looping values were registered during the retention test in the VF-PA group compared with theCONT group (p < 0.05, Cohen's d = 1.49-1.52). The present findings suggest combining video feedback with pedagogical activity during the pandemic induced online coaching or physical education to improve movement learning in school aged children.

Information Processing and Technical Knowledge Contribute to Self-Controlled Video Feedback for Children Learning the Snatch Movement in Weightlifting.

Our aim in this study was to examine, via technical performance analysis and speed of execution, whether information processing and technical knowledge help explain learning benefits of self-controlled video feedback in children's weightlifting performance. We randomized 24 children (aged 10 to 12 years) into self-controlled (SC) and yoked (YK) feedback groups. Learners underwent test sessions one week before (pre-test) and one day after (post-test) six weightlifting training sessions. During each test session, we recorded kinematic parameters of snatch performance using Kinovea version 0.8.15 software. After the learning sessions, the SC group improved on most kinematic parameters (e.g., the horizontal displacement of the bar between the first and the second pulls [MDXV = 25.42%, SD = 18.96, p = 0.003) and the maximum height reached by the bar (MHMV = 5.51%, SD = 7.71, p < 0.05)], while the YK group improved only on the DxV (MDXV = 19.08%, SD = 24.68, p < 0.05). In addition, the SC group showed a more advanced phase of cognitive processing compared to the YK group, and the SC group showed a superior improvement in their technical knowledge level (p < 0.001) compared to the YK group (p < 0.05). Thus, key elements to correcting motor errors in children's weightlifting through self-controlled feedback were improvements in information processing and technical knowledge.

Diurnal variations in physical performances related to football in young soccer players.

PURPOSE: This study investigated the effects of time-of-day on aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests in young soccer players. METHODS: In a counterbalanced and a random order, twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests at two different times-of-day: 07:00 and 17:00 h. During the Yo-Yo test, the total distance (TD) covered and the estimated maximal aerobic velocity (MAV) were determined. The peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) during the RSA test were, also, measured. In addition, during the Wingate test, the peak (P(peak)) and mean (P(mean)) powers were recorded. RESULTS: During the Wingate test, P(peak) and P(mean) were significantly higher at 17:00 than 07:00 h (P<0.05) with diurnal gains of 3.1±3.6 and 2.9±3.5% respectively. During the RSA test, PP during the first two sprints, Pdec and Wtotal were, also, higher in the evening (P<0.05) with amplitudes of 4.8±4.6, 3.1±3.0, 13.1±32.1, and 4.1±2.5% respectively. Likewise, TD and MAV during the Yo-Yo test were higher at 17:00 than 07:00 h with diurnal gains of 13.1±10.7 and 4.2±3.3 respectively. CONCLUSIONS: The present study confirms the daily variations of both aerobic and anaerobic performances during the Yo-Yo, the RSA, and the Wingate tests in trained young Tunisian soccer players.

The effect of training at a specific time-of-day on the diurnal variations of short-term exercise performances in 10- to 11-year-old boys.

The aim of this study was to assess the effect of time-of-day-specific training on the diurnal variations of short-term performances in boys. Twenty-four boys were randomized into a morning-training-group (07:00-08:00h; MTG), an evening-training-group (17:00-18:00h; ETG) and a control-group (CG). They performed four tests of strength and power (unilateral isometric maximal voluntary contraction of the knee extensor muscles, Squat-Jump, Counter-Movement-Jump and Wingate tests) at 07:00 and 17:00h just before (T0) and after 6 weeks of resistance training (T1). In T0, the results revealed that short-term performances improved and oral temperature increased significantly from morning to afternoon (amplitudes between 2.36 and 17.5% for both oral temperature and performances) for all subjects. In T1, the diurnal variations of performances were blunted in the MTG and persisted in the ETG and CG. Moreover, the training program increase muscle strength and power especially after training in the morning hours and the magnitude of gains was greater at the time-of-day-specific training than at other times. In conclusion, these results suggest that time-of-day-specific training increases the child's anaerobic performances specifically at this time-of-day. Moreover, the improvement of these performances was greater after morning than evening training.

Time-of-Day Effects on EMG Parameters During the Wingate Test in Boys.

In boys, muscle power and strength fluctuate with time-of-day with morning nadirs and afternoon maximum values. However, the exact underlying mechanisms of this daily variation are not studied yet. Thus, the purpose of this study was to examine the time-of-day effects on electromyographic (EMG) parameters changes during a Wingate test in boys. Twenty-two boys performed a 30-s Wingate test (measurement of muscle power and fatigue) at 07:00 and 17:00-h on separate days. Surface EMG activity was recorded in the Vastus lateralis, rectus femoris and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root-mean-square (RMS) and mean-power-frequency (MPF) were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Muscle power (8.22 ± 0.92 vs. 8.75 ± 0.99 W·kg(-1) for peak power and 6.96 ± 0. 72 vs. 7.31 ± 0.77 W·kg(-1) for mean power, p < 0.001) and fatigue (30.27 ± 7.98 vs. 34.5 ± 10. 15 %, p < 0.05) during the Wingate test increased significantly from morning to evening. Likewise, MPF (102.14 ± 18.15 vs. 92.38 ± 12.39 Hz during the first 5-s, p < 0.001) and NME (4.78 ± 1.7 vs. 3.88 ± 0.79 W·mV(-1) during the first 5-s, p < 0.001) were higher in the evening than the morning; but no significant time-of-day effect was noticed for RMS. Taken together, these results suggest that peripheral mechanisms are more likely the cause of the child's diurnal variations of muscle power and fatigue during the Wingate test. Key pointsIn boys, performances during the Wingate test fluctuate with the time-of-day.MPF and NME are higher in the evening during the Wingate cycling test.RMS is unaffected by the time-of-day.The evening improvement in muscle power and fatigue is due to an enhancement of the muscle contractile properties.

The effect of ramadan fasting on physical performances, mood state and perceived exertion in young footballers.

PURPOSE: This study was designed to assess the effects of Ramadan fasting on the profile of mood state and perceived exertion in young soccer players and aerobic and anaerobic performances during the Yo-Yo, repeated sprint ability (RSA) and the Wingate tests. METHODS: Twenty junior male soccer players completed the Yo-Yo, the RSA, and the Wingate tests on three different occasions: one-week before Ramadan (BR), the second week (SWR) and the fourth week (ER) of Ramadan. The total distance (TD) covered and the estimated maximal aerobic velocity (MAV) during the Yo-Yo test were recorded. During the RSA test, peak power (PP) during each sprint, the percentage of decrement of PP (PD) and total work (Wtotal) were calculated. During the Wingate test, peak (P(peak)) and mean (P(mean)) powers and fatigue index (FI) were recorded. RESULTS: TD and MAV (P=0.01) during the Yo-Yo test and PP (P=0.01, P=0.004, P=0.001, P=0.01, P=0.03 for sprints 1, 2, 3, 4, and 5, respectively) and Wtotal (P=0.02) during the RSA test were significantly higher during BR than ER. Furthermore, muscle fatigue during the RSA test increased significantly from BR to ER (P=0.01). P(peak) and P(mean) during the Wingate test decreased significantly from BR to SWR and ER (P<0.0005). FI was higher during SWR (P=0.001) and ER (P<0.0005) than BR. In addition, rating of perceived exertion scores and fatigue estimated by the profile of mood state questionnaire were higher during Ramadan in comparison with BR. CONCLUSIONS: The present study suggests that both aerobic and anaerobic performances during the Yo-Yo, the RSA and the Wingate tests were affected by Ramadan fasting in young soccer players.

Time-of-day effects on short-term exercise performances in 10- to 11-year-old boys.

The purpose of this study was to examine the time-of-day effects on short-term performances in boys. In a balanced and randomized study design, 20 boys performed four anaerobic tests of strength and power (grip strength, Squat-Jump, Five-jump and cycle Wingate tests) at 08:00, 14:00 and 18:00 hr on separate days. The results showed a time-of-day effect on oral temperature. Analysis of variance revealed a significant time-of-day effect for short-term performances for strength, cycle, and jump tests. The post hoc analysis revealed that performances improved significantly from morning to afternoon but no significant differences were noticed between 14:00 and 18:00 hr. The differences between the morning and the afternoon (the highest value measured either at 14:00 or at 18:00 hr) reached 5.9% for grip strength, 3.5% for the squat jump test, 5% for the five jump test, and 5.5% for P(peak) and 6% for P(mean) during the Wingate test. A significant positive correlation was found between temperature and short-term performances. In conclusion, a time-of-day effect in the child's maximal short-term exercise performances exists in relation with core temperature. Such variations would have pronounced effects when expressed in training programs and competitions.

Effect of time of day and partial sleep deprivation on short-term, high-power output.

The purpose of this study was to determine whether delaying bedtime or advancing rising time by 4 h affects anaerobic performance of individuals the following day in the morning and afternoon. Eleven subjects participated in the study, during which we measured the maximal, peak, and mean powers (i.e., P(max) [force-velocity test], P(peak), and P(mean) [Wingate test], respectively). Measurements were performed twice daily, at 07:00 and 18:00 h, following a reference normal sleep night (RN), a partial sleep deprivation timed at the beginning of the night (SDB), and a partial sleep deprivation timed at the end of the night (SDE), and oral temperature was measured every 4 h. Each of the three experimental conditions was separated by a one-week period. Our results showed a circadian rhythm in oral temperature, and analysis of variance revealed a significant sleep x test-time effect on peak power (P(peak)), mean power (P(mean)), and maximal power (P(max)). These variables improved significantly from the morning to the afternoon for all three experimental conditions. Whereas the morning-afternoon improvement in the measures was similar after the RN and SDB conditions, it was smaller following the SDE condition. There was no significant difference in the effect of the two sleep-deprivation conditions on anaerobic performances at 07:00 and at 18:00 h under the SDB condition in comparison with the post-reference night. However, the performance variables were significantly lower at 18:00 h after the SDE condition. In conclusion, a 4 h partial sleep deprivation at the end of the night appears to be more disturbing than partial sleep deprivation at the beginning of the night.

Effect of Ramadan on the diurnal variation in short-term high power output.

This study examined the effects of Ramadan fasting on anaerobic performances and their diurnal fluctuations. In a balanced and randomized study design, 12 subjects were measured for maximal power (P(max); force-velocity test), peak power (P(peak)), and mean power (P(mean)) with the Wingate test at 07:00, 17:00, and 21:00 h on four different occasions: one week before Ramadan (BR), the second week of Ramadan (SWR), the fourth week of Ramadan (ER), and two weeks after Ramadan (AR). There was an interval of 28 h between any two successive tests. Oral temperature was measured before each test. Under each condition, the results showed a time-of-day effect on oral temperature. Analysis of variance revealed a significant (Ramadanxtime-of-day of test) interaction effect on P(max). This variable improved significantly from morning to evening before Ramadan (1.1+/-0.2 W x kg(-1)), during the second week of Ramadan (0.6+/-0.2 W x kg(-1)), and two weeks after the end of Ramadan (0.9+/-0.2 W x kg(-1)). However, daily fluctuations disappeared during the fourth week of Ramadan. For P(peak) and P(mean), there was no significant Ramadan x test-time interaction. These variables improved significantly from morning to evening before Ramadan ([1+/-0.3 W x kg(-1)] for P(peak) and [1.7+/-1.6 W x kg(-1)] for P(mean)) and in the second week of Ramadan ([0.9+/-0.6 W x kg(-1)] for P(peak) and [1.7+/-1.5 W x kg(-1)] for P(mean)). However, they were not affected by time-of-day in the fourth week of Ramadan. Considering the effect of Ramadan on anaerobic performances, in comparison with before Ramadan, no significant difference was observed during Ramadan at 07:00 h. The variables were significantly lower in the second week of Ramadan and in the fourth week of Ramadan at 17:00 h and 21:00 h. P(mean) was not affected during the second week of Ramadan. In conclusion, the time-of-day effect on anaerobic power variables tends to disappear during Ramadan. In comparison with the period before Ramadan, anaerobic performances were unaffected in the morning but impaired in the evening during Ramadan.