Sonia Sahli

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 (Pmax; force‐velocity test), peak power (Ppeak), and mean power (Pmean) 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 (Ramadan×time‐of‐day of test) interaction effect on Pmax. This variable improved significantly from morning to evening before Ramadan (1.1±0.2 W · kg−1), during the second week of Ramadan (0.6±0.2 W · kg−1), and two weeks after the end of Ramadan (0.9±0.2 W · kg−1). However, daily fluctuations disappeared during the fourth week of Ramadan. For Ppeak and Pmean, there was no significant Ramadan×test‐time interaction. These variables improved significantly from morning to evening before Ramadan ([1±0.3 W · kg−1] for Ppeak and [1.7±1.6 W · kg−1] for Pmean) and in the second week of Ramadan ([0.9±0.6 W · kg−1] for Ppeak and [1.7±1.5 W · kg−1] for Pmean). 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. Pmean 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.

Individuals with intellectual disability have lower voluntary muscle activation level

The aim of this study was to explore the voluntary activation level during maximal voluntary contraction (MVC) in individuals with intellectual disability (ID) versus individuals without ID using the twitch interpolation technique. Ten individuals with mild ID (ID group) and 10 sedentary men without ID (control group) participated in this study. The evaluation of neuromuscular function consisted in three brief MVCs (3s) of the knee extension superimposed with electrical nerve stimulation (NES) to measure voluntary activation. Muscle activity levels were also measured with surface EMG. The root mean square (RMS) was extracted from the EMG signal. The RMS/Mmax ratio and the neuromuscular efficiency (NME) were calculated. Our results reported that individuals with ID present lower muscle strength (p < 0.001), lower voluntary activation level (p < 0.001), lower RMS values of vastus lateralis (p < 0.05), vastus medialis (p < 0.05), and rectus femoris (p < 0.001) muscles. In addition, our results showed lower RMS/Mmax values in the ID group than in the control group for the VM (0.05 ± 0.01 mV vs. 0.04 ± 0.01 mV; p < 0.05) and the RF (0.06 ± 0.02 mV vs. 0.05 ± 0.02 mV; p < 0.05) muscles. However, no significant difference was reported for the VL muscle (0.05 ± 0.02 mV vs. 0.05 ± 0.02 mV; p=0.463). Moreover, Individuals with ID present smaller potentiated twitch (p < 0.001). However, no significant difference was reported in the NME ratio. These results suggest that the lower muscle strength known in individuals with ID is related to a central nervous system failure to activate motor units and to some abnormal intrinsic muscle properties. It seems that the inactive lifestyle adopted by individuals with ID is one of the most important factors of their lower voluntary activation levels. Therefore, physical activities should be introduced in life style of individuals with ID to improve their neuromuscular function.

Neuromuscular fatigue during high-intensity intermittent exercise in individuals with intellectual disability

This study examined neuromuscular fatigue after high-intensity intermittent exercise in 10 men with mild intellectual disability (ID) in comparison with 10 controls. Both groups performed three maximal voluntary contractions (MVC) of knee extension with 5 min in-between. The highest level achieved was selected as reference MVC. The fatiguing exercise consists of five sets with a maximal number of flexion-extension cycles at 80% of the one maximal repetition (1RM) for the right leg at 90° with 90 s rest interval between sets. The MVC was tested again after the last set. Peak force and electromyography (EMG) signals were measured during the MVC tests. Root Mean Square (RMS) and Median Frequency (MF) were calculated. Neuromuscular efficiency (NME) was calculated as the ratio of peak force to the RMS. Before exercise, individuals with ID had a lower MVC (p<0.05) and a lower RMS (p<0.05). No significant difference between groups in MF and NME. After exercise, MVC decreases significantly in both groups (p<0.001). Individuals with ID have greater force decline (p<0.001 vs. p<0.01). RMS decreased significantly (p<0.001) whereas the NME increased significantly (p<0.05) in individuals with ID, but both remained unchanged in controls. The MF decreased significantly in both groups (p<0.001). In conclusion, individuals with ID presented a lower peak force than individuals without ID. After a high-intensity intermittent exercise, individuals with ID demonstrated a greater force decline caused by neural activation failure. When rehabilitation and sport train ID individuals, they should consider this nervous system weakness.

Time-of-day effects on postural control and attentional capacities in children

The present study aimed to examine the effect of time-of-day on postural control, body temperature, and attentional capacities in 5-6 year old children. Twelve male children (5-6-year-old) were asked to maintain an upright bipedal stance on a force platform with eyes open (EO) and eyes closed (EC) at 07:00, 10:00, 14:00, and 18:00 h. Postural control was evaluated by center of pressure (CoP) surface area (CoPArea), CoP mean velocity (CoPVm), length of the CoP displacement as a function of the surface (LFS) ratio and Rombergs index (RI). Oral temperature and the simple reaction time were also recorded at the beginning of each test session. The one way ANOVA (4 time-of-day) showed significant time-of-day effects on CoPArea (p<0.001), CoPVm (p<0.01), LFS ratio (p<0.001) and RI (p<0.01). Childrens postural control was lower at 07:00 h and at 14:00 h in comparison with 10:00 h and 18:00 h. Likewise, the reaction time was significantly (p<0.001) better at 10:00 h and 18:00 h in comparison with 07:00 h and 14:00 h. Oral temperature was higher at 14:00 h and 18:00 h than 08:00 h and 10:00 h (p<0.001). In conclusion, the childrens postural control fluctuates during the daytime (i.e., better postural control at 10:00 h and at 18:00 h) with a diurnal rhythm close to that of body temperature and attentional capacities. Therefore, the evaluation of changes in postural control of 5-6-year-old children using force plate measures is recommended in the middle morning or the late afternoon to avoid the post-awakening and the post-prandial phases.

The effect of a combined strength and proprioceptive training on muscle strength and postural balance in boys with intellectual disability: An exploratory study.

The aim of our study was to investigate the effect of a combined strength and proprioception training (CSPT) program on muscle strength and postural balance in children with intellectual disability (ID). The maximum voluntary contraction (MVC) and postural parameters (CoPVm, CoPLX, CoPLY) of 20 children with ID were recorded before and after 8 weeks of a CSPT program. The participants were divided into two groups: an experimental group who attended a CSPT program and a control group who continued with daily activities. In the trained group, the MVC increased significantly (p<0.001) after the training period and the postural parameters decreased significantly in Double-Leg Stance (DLS) and One-Leg Stance (OLS) during the firm surface condition as well as in the DLS during the foam surface condition; in both eyes open (EO) and eyes closed (EC) conditions. A CSPT program improves postural balance in children with ID could be due to the enhancement in muscle strength and proprioceptive input integration.

An open‐label randomized control trial of hopping and jumping training versus sensorimotor rehabilitation programme on postural capacities in individuals with intellectual disabilities

BACKGROUND This study aimed to compare the effectiveness of a hopping and jumping training programme (HJP) versus a sensorimotor rehabilitation programme (SRP) on postural performances in children with intellectual disability. METHODS Three groups of children with intellectual disability participated in the study: the HJP group, the SRP group and a control group. Postural capacities were tested with the Berg Balance Scale (BBS) and the Tinetti tests. The HJP and the SRP groups participated in the training programmes for eight weeks. Then, all participants were retested. RESULTS Results showed that before the training period, there are no significant differences between the three groups. After the training period, the BBS and the Tinetti scores increased significantly in the HJP group and the SRP group with greater extent in the HJP group than in the STP group. CONCLUSION We suggest that HJP training is more recommended to improve postural capacities in children with intellectual disability.

Combined physical-cognitive training enhances postural performances during daily life tasks in older adults

ABSTRACT Physical‐cognitive interventions seem promising to improve balance and gait performances and prevent falls in the elderly. Although these beneficial effects, it is still not clear whether these physical‐cognitive training modalities leads to more general non‐specific adaptations that can be transferred to some measures reflecting every day abilities. This randomized controlled trial examined postural (center of pressure oscillations), physical (lower body strength, gait speed, functional mobility, dynamic balance) and cognitive performances (reaction time) and postural performance during daily life tasks (walking while conversing on a phone and maintaining an upright standing posture while buttoning a shirt) in older adults (66.29 ± 3.61 years) pre‐ and post‐ 6‐months physical and physical‐cognitive interventions. Results showed that both training modalities improve balance (p < 0.001), physical functions (p < 0.01) and attention (p < 0.001) in older adults. Only simultaneous physical‐cognitive training enhances performance in daily life tasks. Three months after the intervention, these improvements were generally maintained for physical functions and attention and were not maintained for the postural performances in daily life task. In conclusion, physical training improves postural balance, mobility, attention and physical functions in older adults. Only simultaneous physical‐cognitive training modality enhances performance in some tasks relative to every day abilities. Nonetheless, these gains were lost after 3 months of detraining period suggesting a need for older people to participate regularly in such training for their daily life independence. HIGHLIGHTSPhysical‐cognitive training enhances postural control in daily life functions.These enhancements are not maintained 3 months after the end of the training.Physical and physical‐cognitive training improve physical and postural performances.

Kung-fu versus swimming training and the effects on balance abilities in young adolescents

OBJECTIVE Our purpose is to investigate the static balance control of young adolescents practicing kung-fu and swimming in order to find out which of these physical activities is the most effective in developing specific balance abilities in young adolescents. DESIGN Comparative experimental study. SETTING University laboratory research. PARTICIPANTS Three groups of 11-13-year-old boys (12 practicing Kung-Fu, 12 practicing swimming and 12 controls). MAIN OUTCOME MEASURES Center of pressure (CoP) excursions were registered in upright bipedal and unipedal stances on a stabilometric force platform in eyes open (EO) and eyes closed (EC) conditions. RESULTS Kung-fu practitioners control their balance (P < .05) better than controls and swimmers in the unipedal posture when visual inputs are available. Kung-fu training improved (P < .05) the bipedal balance control in the EO condition. However, swimming training developed (P < .05) bipedal balance control in both EO and EC conditions. The swimmers showed a lower reliance on vision (P < .05) compared to kung-fu practitioners. CONCLUSIONS Both of these physical activities could be recommended for young adolescents as recreational or rehabilitation programs as they develop specific balance abilities that could be important for improving and maintaining optimal health.

Effect of heavy isokinetic intermittent exercise on acute neuromuscular fatigue in knee extensors

This study aimed at quantifying maximal voluntary force-generating capacity of the quadriceps femoris and its EMG output after an isokinetic concentric intermittent exercise. Another objective was to find out whether the amount of neuromuscular fatigue was velocity-dependent. Eight males judo players (age: 18.4 ± 1.4 years; height: 1.80 ± 0.03 m; body mass: 77.0 ± 4.2 kg) performed a fatiguing exercise composed of five sets of ten maximal knee extension at 120°/s, with 3min recovery in between. Peak torque (PT) at three angular velocities (60, 120 and 180°/s) and EMG from the vastus lateralis, rectus femoris and vastus medialis were evaluated before and after the fatiguing exercise. EMG was analyzed for root mean square (RMS) and median frequency (MF). The fatiguing exercise induced PT decrement (P< 0.01) irrespective of the test velocity, in conjunction with decreased RMS (P< 0.001) and a decrease in MF (P< 0.01). In addition, although EMG activity demonstrated no velocity effect, the loss of PT after the fatiguing isokinetic intermittent exercise was more pronounced at the lower velocity (P< 0.05). The combination of decreased PT, RMS and MF suggests a reduction of the neural drive under the present fatiguing protocol.

Self-confidence and affect responses to short-term sprint interval training

The study aimed to investigate the effects of repeated sprint (RS) training on somatic anxiety (SA), cognitive anxiety (CA), self-confidence (SC), rating of perceived exertion (RPE) and repeated sprint ability (RSA) indicators in elite young soccer players. Thirty elite soccer players in the first football league (age: 17.8±0.9years) volunteered to participate in this study. They were randomly assigned to one of two groups: a repeated sprint training group (RST-G; n=15) and a control group (CON-G; n=15). RST-G participated in 6weeks of intensive training based on RS (6×(20+20m) runs, with 20s passive recovery interval between sprints, 3 times/week). Before and after the 6-week intervention, all participants performed a RSA test and completed a Competitive Scale Anxiety Inventory (CSAI-2) and the RPE. After training RST-G showed a very significant (p<0.000) increase in RSA total time performance relative to controls. Despite the faster sprint pace, the RPE also decreased significantly (p<0.005) in RST-G, and their self confidence was significantly greater (p<0.01), while the cognitive (p<0.01) and somatic (p<0.000) components of their anxiety state decreased. When practiced regularly, short bouts of sprint exercises improve anaerobic performance associated with a reduction in anxiety state and an increase in SC which may probably boost competitive performance.