Effects of running exercises on reaction time and working memory in individuals with intellectual disability.

BACKGROUND: This study explored the effect of running exercises at low [30% heart rate reserve (HRR)] and moderate (60%HRR) intensities on cognitive performances in individuals with intellectual disability (ID). METHODS: Participants performed randomly reaction time (RT) tests: visual RT [simple RT (SRT) and choice RT (CRT)], auditory SRT (ASRT) and working memory (WM) (Corsi test) before and after the exercises. RESULTS: The results showed that after both exercises, SRT decreased significantly (P < 0.001) in both groups with higher extent (P < 0.05) at 60%HRR compared with 30%HRR. CRT decreased (P < 0.01), similarly, after the both exercises in both groups with higher (P < 0.001) extent in the intellectual disability group (IDG). ASRT decreased significantly, at 30%HRR, in IDG (P < 0.001) and in control group (CG) (P < 0.01) with greater extent in IDG (P < 0.001). At 60%HRR, ASRT decreased significantly in both groups (P < 0.001) with greater extent in IDG (P < 0.001). The ΔASRT% was significantly (P < 0.05) higher at 30%HRR compared with 60%HRR in IDG. In CG, no significant (P = 0.21) difference was reported between intensities. The Corsi forward and the Corsi backward scores increased significantly (P < 0.01) in both groups after both intensities with higher extent in IDG (P < 0.01). CONCLUSIONS: Our results suggest that low and moderate running exercises improve similarly simple and choice visual RT as well as WM in individuals with ID. Furthermore, low-intensity exercise could be more appropriate to enhance ASRT compared the moderate one in these individuals. Therefore, low-intensity exercise seems to be an efficient strategy to improve cognitive performances in individuals with ID.

Neuromuscular characteristics in trained vs. sedentary male adults with intellectual disability.

BACKGROUND: This study aimed to explore muscle strength production and its underlying neuromuscular characteristics in sedentary and trained individuals with intellectual disability (ID) compared with healthy sedentary individuals. METHODS: Three adult groups (age: 25.07 ± 0.70) consisting of sedentary individuals with ID (IDSG), trained individuals with ID (IDTG) and a control group (CONT) participated in the present study. Peak torque (PT) during maximal voluntary isometric contraction, voluntary activation level (VAL), surface electromyography (sEMG) recordings, electrophysiological (Mmax ) and potentiated twitch torque (PTT responses) of the knee extensor muscles and thigh muscle volume were assessed. RESULTS: Compared with CONT and IDTG, respectively, IDSG presented significantly lower PT (-48% and -42%), VAL (-24% and -9%), sEMG (-49% and -29%), Mmax (-41% and -39%) and PTT (-32% and -28%) values. These deficits were reduced between IDTG compared with CONT (i.e. PT: -10%; VAL: -16%; and sEMG: -28%) or did not differ anymore (PTT and Mmax ). Normalising PT to thigh muscle volume and/or computing theoretical PT value overwhelm strength production differences between IDTG and CONT. Training background influences the outcomes with IDTG exhibiting greater PT, VAL, sEMG, Mmax and PTT than IDSG. CONCLUSIONS: Strength production deficit in IDSG was related to both muscular and neural characteristics compared with healthy controls whereas this deficit mainly arises from neural characteristics for IDTG.

Electrostimulation Training Effects on diurnal Fluctuations of Neuromuscular Performance.

This study examined the effects of electrostimulation (ES) strength training at the same time-of-day on the diurnal fluctuations of maximal voluntary isometric contractions (MVIC) and surface electromyography (EMG). 20 male performed 3 MVICs of knee extension coupled with surface EMG before and after 5 weeks of 3 ES training sessions per week. Each ES training session consisted in 45 isometric contractions. The participants were randomly assigned to either a morning (MTG, 07:00-08:00 h) or an evening (ETG, 17:00-18:00 h) training group. Both groups performed the evaluation tests at 07:00 and 17:00 h. Before ES training, MVIC was significantly higher in the evening compared to the morning for all groups, but there was no significant difference between groups for all EMG parameters. After the ES training, the diurnal variations in MVIC were blunted in the MTG and persisted in the ETG. Significant time-of-day effect was noticed for all EMG parameters but there was no group effect. The elimination of the diurnal fluctuations of MVIC and the appearance of EMG variations by training in the morning hours suggest that neural adaptations are the main source of temporal specificity of neuromuscular performance after ES strength training.

Effects of Ramadan Gasting on Postural Balance and Attentional Capacities in Elderly People.

OBJECTIVE: To evaluate the effects of Ramadan fasting on postural balance and attentional capacities in older adults. SETTING: the Neurophysiology department of a University Hospital. PARTICIPANTS: Fifteen males aged between 65 and 80 years were asked to perform a postural balance protocol and a simple reaction time (SRT) test in four testing phases: one week before Ramadan (BR), during the second (SWR) and the fourth week of Ramadan (FWR) and 3 weeks after Ramadan (AR). MEASUREMENTS: Postural balance measurements were recorded in the bipedal stance in four different conditions: firm surface/eyes open (EO), firm surface/eyes closed (EC), foam surface/EO and foam surface/EC using a force platform. RESULTS: Results of the present study demonstrated that center of pressure (CoP) mean velocity (CoPVm), medio-lateral length (CoPLX) and antero-posterior length (CoPLY) were significantly higher during the SWR than BR. Likewise, values of CoPVm and CoPLX increased significantly during the FWR compared to BR. The CoPLX decreased significantly in the FWR compared to the SWR. Values of CoPVm and CoPLX were significantly higher AR in comparison with BR. In addition, SRT values increased significantly during the SWR and the FWR than BR. CONCLUSION: Ramadan fasting affects postural balance and attentional capacities in the elderly mainly in the SWR and it may, therefore, increase the risk of fall and fall-related injuries. More than three weeks are needed for older adults to recover postural balance impairment due to Ramadan fasting.

Improved tolerance of peripheral fatigue by the central nervous system after endurance training.

PURPOSE: The purposes of this study were to evaluate the effect of endurance training on central fatigue development and recovery. METHODS: A control group was compared to a training group, which followed an 8-week endurance-training program, consisting in low-force concentric and isometric contractions. Before (PRE) and after (POST) the training period, neuromuscular function of the knee extensor (KE) muscles was evaluated before, immediately after and during 33 min after an exhausting submaximal isometric task at 15 % of the maximal voluntary contraction (MVC) force. After training, the trained group performed another test at iso-time, i.e., with the task maintained until the duration completed before training was matched (POST2). The evaluation of neuromuscular function consisted in the determination of the voluntary activation level during MVCs, from peripheral nerve electrical (VAPNS) and transcranial magnetic stimulations (VATMS). The amplitude of the potentiated twitch (Pt), the evoked [motor evoked potentials, cortical silent period (CSP)] and voluntary EMG activities were also recorded on the KE muscles. RESULTS: Before training, the isometric task induced significant reductions of VAPNS, VATMS and Pt, and an increased CSP. The training period induced a threefold increase of exercise duration, delayed central fatigue appearance, as illustrated by the absence of modification of VAPNS, VATMS and CSP after POST2. At POST, central fatigue magnitude and recovery were not modified but Pt reduction was greater. CONCLUSION: These results suggest that central fatigue partially adapts to endurance training. This adaptation principally translates into improved tolerance of peripheral fatigue by the central nervous system.

Reducing resistance training volume during Ramadan improves muscle strength and power in football players.

We aimed to examine the effect of maintaining or reducing resistance training volume during Ramadan-intermittent-fasting (RIF) on short-term maximal performances. 20 footballers (age: 18.4 ± 0.8 years; body-mass: 72.4 ± 4.1 kg; height: 183.4 ± 4.6 cm) were matched and randomly assigned to a normal-training-group (G1) or a tapering-group (G2). They were tested for muscular strength (maximal-voluntary-contraction) and power (squat-jump and counter-movement-jump) 1 month before RIF (T0), 1 week before RIF (T1), after 2 weeks of fasting (T2) and at the end of RIF (T3). From T1 to T2, subjects performed a whole-body resistance training program (8-repetitions × 4-sets with 4-min recovery in-between). During RIF, G1 maintained the same training program, while G2 performed a period of reduced training volume (3 sets/exercise; - 22%). Muscle strength and power increased significantly from T0 to T1, from T0 to T2 and from T0 to T3 in G1 and G2 and from T1 to T2 and from T1 to T3 only in G2 (p<0.05). Performance was higher in G2 than G1 during T2 (p<0.01). Moreover, the ∆-change of performance between T0 and T2 and T3 was significantly higher in G2 than G1 (p<0.05). For young soccer players, a tapering period characterized by a reduced training volume during RIF may lead to significant improvement in muscle strength and power.

Anaerobic upper and lower body power measurements and perception of fatigue during a kick boxing match.

AIM: Objective of the study was to determine the effects of a kick-boxing match on muscle power of the upper and lower body as well as the associated perceived exertion in young men. METHODS: Eighteen well trained kick-boxers volunteered to participate in a competitive sparring bout preceded and followed by three anaerobic tests as follow: squat jump (SJ) and counter movement jump (CMJ) for legs and 30-s Wingate test for arms. The sparring bout consisted of three 2 min rounds with 1 min recovery period in-between. Blood lactate (BL), heart rate (HR) and rating of perceived exertion (RPE) were analyzed before and after each round. RESULTS: The results showed that vertical jump distance in SJ and CMJ were significantly lower after the kick-boxing match (27.92±3.84 vs. 25.28±4.39 cm; 29.8±5.33 vs 28.48±4.64 cm, for SJ and CMJ respectively). Likewise, peak and mean power in the Wingate test decreased significantly after the sparring bout (5.89±0. 69 vs. 5.26±0.66 W•kg-1 and 4.51±0.53 vs. 4.12±0.51 W•kg-1 for PP and MP respectively; P<0.001). Moreover, we found a significant increase in BL, HR, and RPE after the kick-boxing match (P<0.001). BL increased significantly after the second and third round from the post round one values' (P<0.001). CONCLUSION: These findings showed that a single kick-boxing match is of sufficient intensity to stress the anaerobic metabolism. Thus, training protocols should include exercises that train the anaerobic energetic pathways for upper and lower body.

Time of day effects on repeated sprint ability.

The present study aimed at investigating the effects of time-of-day on muscle power and associated electromyographic (EMG) activity level of 4 thigh muscles during a repeated pedalling sprint exercise. After a familiarization session, 12 male subjects were asked to perform the repeated sprint ability test during 2 experimental sessions (randomized order), which were set up either at 06:00 or 18:00 h. For each sprint, peak power output, percentage of peak power decrement and total work were calculated. EMG activity of vastus lateralis, rectus femoris, vastus medialis and biceps femoris muscles was recorded throughout the test and analyzed for each sprint. Total work and percentage of peak power decrement were higher in the evening than in the morning (p<0.01 and p<0.05, respectively). Likewise, peak power was significantly higher at 18:00 than 06:00 h during the first 3 sprints (p<0.01 for sprint 1 and p<0.05 for sprint 2 and 3). There was no time-of-day effect for EMG activity level. The neuromuscular efficiency decreased significantly over the repeated sprint ability test at the 2 times of testing (p<0.01). Despite diurnal fluctuation in muscular power and neuromuscular fatigue during the repeated sprint ability test, EMG activity of major thigh muscles was not time-of-day dependent.

[Comparison of two electrical stimulation protocols on quadriceps muscle after anterior cruciate ligament surgery. Feasability study]. / Etude comparative de deux protocoles d'électrostimulation du quadriceps après chirurgie du ligament croisé antérieur. Etude de faisabilité.

OBJECTIVES: To evaluate the feasibility of a study comparing the effects of two protocols of electrical stimulation of the quadriceps femoris after anterior cruciate ligament surgery. MATERIAL: Seven sportsmen with a mean age of 26 yrs were randomly grouped in two: a 20 Hz stimulated group (4 patients) and a 80 Hz stimulated group (3 patients). After surgery all patients received electrical stimulation of the quadriceps femoris, five days a week, for 12 weeks, and had a standard program of voluntary contractions. The main outcome assessed before and three months after surgery were: quadriceps and hamstring peak torque at 90, 180 and 240 degrees /second, maximal isometric quadriceps at 75 degrees of flexion and muscle and subcutaneous fat volumes of the thigh using MRI. RESULTS: After 12 weeks of rehabilitation, the thigh muscle volume deficit of the operated limb was between 3 and 9% in the 20 Hz stimulated group and between 1 and 2% in the 80 Hz stimulated group. Quadriceps peak torque deficit was less than 30% except for two patients in the 20 Hz stimulated group. Maximal isometric quadriceps deficit of the operated limb was higher than 30% except for two patients in the 20 Hz stimulated group. CONCLUSION: The study showed that comparison of two protocols of electrical stimulation of the quadriceps femoris after anterior cruciate ligament surgery is possible if stimulation period is not more than four weeks.

Effects of two electrical stimulation frequencies in thigh muscle after knee surgery.

The purpose of this study was to compare the effects of two protocols of electrical stimulation combined with voluntary contractions on the recovery of thigh muscles after anterior cruciate ligament (ACL) surgery. Ten sportsmen with a mean age of 26 yrs were randomly assigned into two groups: a 80 Hz stimulated group (5 patients) and a 20 Hz stimulated group (5 patients). All patients received electrical stimulation of the quadriceps femoris, five days a week, for 12 weeks, and had a standard program of voluntary contractions. Muscle and fat volumes of the thigh were assessed using MRI before surgery and after 12 weeks of rehabilitation. Quadriceps and hamstring muscle strength were evaluated by isokinetic measurements. Twelve weeks after surgery, the quadriceps peak torque deficit in the operated limb with respect to the non operated limb at 180 degrees /s and 240 degrees /s was significantly (p < 0.05) less in the 20 Hz group than in the 80 Hz group. This difference was not confirmed when comparing the pre-surgery quadriceps peak torque of the operated limb with the post-surgery one. Subcutaneous fat volume was increased for the two groups at the post-surgery test. This increase was significantly (p < 0.05) greater for the 80 Hz group. Thigh muscle volume deficit was not significantly different between the two groups.