Efficacy of lateral stair walking training in patients with chronic stroke: A pilot randomized controlled study

BackgroundPatients with chronic stroke have reduced capacity for performing activities of daily living (ADLs) and are at increased risk for falls during walking due to long-term changes to muscle tone and force, as well as movement control.Research questionTo investigate the efficacy of lateral stair walking training on muscle strength of affected lower extremities, balance, ADLs, and gait ability in patients with chronic stroke.MethodsThe experimental group received 15 min of lateral stair walking exercise along with 15 min of traditional physiotherapy, whereas the control group received only traditional physiotherapy for 30 min. Both groups received the intervention once a week for 12 weeks. Outcome measurements included muscle strength, postural assessment scale for stroke patients (PASS), Fugal–Meyer assessment for lower extremity (FMA-LE), Barthel index (BI), timed up and go test (TUG), and the gait parameters which were determined by the Reha-Watch system.ResultsA total of 24 participants completed the study. The experimental group showed significant improvements in hip extensor, flexor, and abductor strength of the affected limb, FMA-LE, BI, TUG, and gait parameters of stride length, velocity, and cadence. Significant differences in affected limb ankle plantar strength (p = 0.024), PASS (p = 0.017), BI (p = 0.039), TUG (p = 0.049), and gait velocity (p < 0.001) were observed between the 2 groups.SignificanceLateral stair walking training alongside physical therapy resulted in significant improvements in hip muscle strength and gait parameters in patients with chronic stroke. Our results support the incorporation of lateral stair walking training into clinical rehabilitation programs. Lateral stair walking training in patients with chronic stroke can be used as an effective treatment to improve gait, balance performance, and ADLs.     

Differences in lower extremity muscular coactivation during postural control between healthy and obese adults

IntroductionIt is well established that obesity is associated with deterioration in postural control that may reduce obese adults’ autonomy and increase risks of falls. However, neuromuscular mechanisms through which postural control alterations occur in obese adults remain unclear.ObjectiveTo investigate the effects of obesity on muscle coactivation at the ankle joint during static and dynamic postural control.Materials and methodsA control group (CG; n = 20; age = 32.5 ± 7.6 years; BMI = 22.4 ± 2.2 Kg/m²) and an obese group (OG; n = 20; age = 34.2 ± 5.6 years; BMI = 38.6 ± 4.1 Kg/m²) participated in this study. Static postural control was evaluated by center of pressure (CoP) displacements during quiet standing. Dynamic postural control was assessed by the maximal distance traveled by the CoP during a forward lean test. Electromyography activity data for the gastrocnemius medialis (GM), soleus (SOL) and tibialis anterior (TA) were collected during both quiet standing and forward lean tests. Muscle activities were used to calculate two separate coactivation indexes (CI) between ankle plantar and dorsal flexors (GM/TA and SOL/TA, respectively).ResultsCoP displacements were higher in the OG than in the CG for quiet standing (p < 0.05). When leaning forward, the maximal distance of the CoP was higher in the CG than in the OG (p < 0.05). Only the CI value calculated for SOL/TA was higher in the OG than in the CG for both static and dynamic tasks (p < 0.05). The SOL/TA CI value in the OG was positively correlated with CoP displacements during quiet standing (r = 0.79; p < 0.05).ConclusionObesity increases muscle coactivation of the soleus and tibialis anterior muscles at the ankle joint during both static and dynamic postural control. This adaptive neuromuscular response may represent a joint stiffening strategy for enhancing stability. Consequently, increased ankle muscle coactivation could not be considered as a good adaptation in obese adults.     

Intra-limb coordination deficit in stroke survivors and response to treatment

PURPOSE: Purpose one was to characterize the consistency of intra-limb hip/knee (H/K) coordination according to a measure of average coefficient of correspondence (ACC) across strides. Purpose two was to investigate H/K ACC validity and ability to discriminate pre-/post-treatment change in stroke survivors. METHODS: Five healthy controls and 32 chronic (>12 mos) stroke survivors were enrolled, and H/K ACC was calculated for both groups. Comparison between controls and stroke was made using the Mann-Whitney Test. Convergent validity of H/K ACC was tested using the Pearson Correlation model with gait speed and the 6 min Walk Test (6MWT). Stroke survivors were randomized to either: (1) gait training with functional neuromuscular stimulation (FNS) using intramuscular (IM) electrodes or (2) gait training without FNS. Both groups had treatment 1.5 h/day, 5 days/week, for 12 weeks, including .5 h coordination exercise, .5 h body weight supported treadmill training (BWSTT), and .5 h over ground gait training. The FNS-IM group used FNS-IM for all treatment components; the No-FNS group did not. Pre-/post-treatment comparisons were made using ANOVA. RESULTS: H/K ACC detected a significant difference between controls versus stroke involved limb (p=.0001) and controls versus stroke uninvolved limb (p=.042). The H/K ACC measure was well-correlated with gait speed (r=.70) and 6MWT (r=.69). H/K ACC showed a significant treatment response to FNS-IM (p=.003), but not No-FNS (p=.747). CONCLUSIONS: H/K ACC sensitively discriminated between controls versus stroke involved or uninvolved limbs. H/K ACC was valid, with significant correlations with both walking speed and 6MWT. FNS-IM produced a significant gain in H/K ACC, and No-FNS did not.     

Patellar tendinopathy impairs postural control in athletes: A case-control study

ObjectiveTo compare postural control performance between athletes with and without patellar tendinopathy (PT).DesignCase-control study.ParticipantsFifty-eight athletes, 29 with PT (PT group: PTG) and 29 healthy ones (control group: CG).Main outcome measuresStatic and dynamic postural control were assessed with a force platform and the Y-Balance Test (Y-BT), respectively. Quadriceps strength of both limbs was evaluated using an isometric dynamometer.ResultsThe PTG exhibited significantly (p < 0.05) higher centre of pressure (CoP) values than the CG on the foam surface, and significantly lower (p < 0.001) anterior, posteromedial and posterolateral normalized reach distances, and composite score in dynamic postural control on the injured limb (IL) compared to non-injured limb (NIL) and dominant limb (DL) of the CG. The quadriceps muscle strength was significantly lower on the IL compared to the NIL (p < 0.01) and DL (p < 0.05) of the CG.ConclusionAthletes suffering from PT exhibited worse static and dynamic postural control compared to healthy peers. As players with PT frequently continue training despite their tendon pain, physiotherapists and clinicians should incorporate balance rehabilitation programs in the treatment of these players, not only to prevent further potential injuries but also to enhance sport performance.     

Effects of resistance training on H+ regulation, buffer capacity, and repeated sprints

PURPOSE: We investigated the effects of resistance training on muscle buffer capacity, H regulation, and repeated-sprint ability (RSA). METHODS: Sixteen recreationally active females performed a graded exercise test to determine VO2peak and the lactate threshold (LT), a repeated-sprint test (5 x 6 s, every 30 s) to determine RSA, and a 60-s high-intensity exercise test based on their pretraining RSA score (CIT60; continuous cycling at approximately 160% VO2peak). Muscle biopsies (vastus lateralis) were sampled before and immediately after CIT60. Subjects were then randomly assigned to either a high-repetition (three to five sets of 15-20 reps) short-rest (20 s) resistance-training group or to a control group. RESULTS: Training did not result in significant improvements in VO2peak (P > 0.05) but did improve the LT, leg strength, and RSA (P < 0.05). There were no significant improvements in muscle buffer capacity after training (P > 0.05); however, there was a significant reduction in H in the muscle and blood after high-intensity exercise (CIT60) (P < 0.05), CONCLUSIONS: High-repetition, short-rest, resistance training does not improve muscle buffer capacity in active females, but it does reduce H accumulation during high-intensity exercise (approximately 160% VO2peak). It is likely that increases in strength, LT, and ion regulation contributed to the improved RSA.     

Effect of a 13-week aerobic training programme on the maximal power developed during a force-velocity test in prepubertal boys and girls.

The present study was undertaken in order to evaluate the effect of an aerobic training programme on the maximal power (Pmax) developed during a short-term exercise test in prepubertal children. Thirty-three 10-11 year old boys and girls were investigated: 17 (TG) participated twice a week (1 h per session) in a 13-week running programme and 16 (CG) served as a control group. Pmax was measured during a force-velocity test conducted on a friction-loaded cycle ergometer. The force (Fopt) and velocity (Vopt) at which Pmax was obtained were determined. Lower limb muscle mass (LMM) was evaluated by means of dual X-ray absorptiometry. Following training, Pmax increased even when muscle mass change due to the growth process was taken into account (Pmax W: + 23 %, W x kg(-1) LMM: + 18%, p < 0.001). The increase in Fopt was principally responsible for such an improvement since no alteration was noticed for Vopt after training. As for Pmax, Fopt was still greater following training when LMM was taken into account (p < 0.01). Furthermore, no changes were noticed for CG for all variables evaluated during the anaerobic test after the study period. Differences between TG and CG regarding Pmax and Fopt were obtained after training only. In conclusion this study highlights the effectiveness of an aerobic training programme to improve the maximal power during short-term exercise in prepubertal children.     

Posture-related changes in hemodynamics in humans after administration of sidnocarb and its combination with obsidan

Experiments were carried out to study the effect of sydnocarb 3-(beta-phenylisopropyl)-N-phenylcarbamoyl-sydnonimine), a stimulant of mental and physical performance, and its combination with obsidan, a beta-adrenoblocking agent, on the central and peripheral hemodynamics during a head-up test (+75 degrees) after a 6-hour head-down tilt (-15 degrees). Sydnocarb increased the tone of brain and leg arterioles, left unchanged stroke volume and cardiac output, and decreased the postural increment of heart rate. Sydnocarb (15 mg) combined with obsidan (20 mg) reduced heart rate and its postural increment, increased stroke volume, and increased the tone of resistive vessels, as was also the effect of sydnocarb taken separately.     

Effects of plyometric training followed by a reduced training programme on physical performance in prepubescent soccer players

BACKGROUND: In adult population, stretch-shortening cycle exercise (plyometric exercise) is often used to improve leg muscle power and vertical jump performance. In children, limited information regarding this type of exercise is available. The purpose of this study was to examine the effectiveness of plyometric training and maintenance training on physical performances in prepubescent soccer players. METHODS: Twenty boys aged 12-13 years was divided in two groups (10 in each): jump group (JG) and control group (CG). JG trained 3 days/week during 10 weeks, and performed various plyometric exercises including jumping, hurdling and skipping. The subsequent reduced training period lasted 8 weeks. However, all subjects continued their soccer training. Maximal cycling power (Pmax) was calculated using a force-velocity cycling test. Jumping power was assessed by using the following tests: countermovement jump (CMJ), squat jump (SJ), drop jump (DJ), multiple 5 bounds (MB5) and repeated rebound jump for 15 seconds (RRJ15). Running velocities included: 20, 30 and 40 m (V20, V30, V40 m). Body fat percentage (BF percent) and lean leg volume were estimated by anthropometry. RESULTS: Before training, except for BF percent, all baseline anthropometric characteristics were similar between JG and CG. After the training programme, Pmax (p<0.01), CMJ (p<0.01), SJ (p<0.05), MB5 (p<0.01), RRJ15 (p<0.01) and V20 m (p<0.05), performances increased in the JG. During this period no significant performance increase was obtained in the CG. After the 8-week of reduced training, except Pmax (p<0.05) for CG, any increase was observed in both groups. CONCLUSIONS: These results demonstrate that short-term plyometric training programmes increase athletic performances in prepubescent boys. These improvements were maintained after a period of reduced training.     

Functional output improvement in FES cycling by means of forced smooth pedaling

PURPOSE: Investigation of the influence of forced smooth and normal (nonsmooth) pedaling on the functional output of outdoor functional neuromuscular electrical stimulation (FES)-propelled cycling of spinal cord-injured subjects. SUBJECTS: Twelve subjects with complete spinal cord injury (T4-T12) and limited previous FES training. METHOD: Each subject participated in two separate outdoor sessions: once while pedaling a tricycle in a fixed gear, and a second time while free pedaling the same tricycle; both times with FES. Data on distance covered until exhaustion, cadence, and pedal forces were collected. Energy balance calculations led to evaluations of jerk loss and joint-related concentric/eccentric work. RESULTS: First-trial and total session distances were 68 and 103% longer, respectively, in the forced smooth cycling session than in the free cycling session (P < 0.001). Significantly more additional crank work (accompanied by increased concentric work production) was generated in nonsteady cycling phases to overcome increased jerk losses during free than during fixed-gear pedaling. During fixed-gear pedaling, timing and joint location of muscle work generation were more similar to the cycling of able-bodied subjects than during freewheel pedaling, because most work was generated by knee extensors in the power phase during the former pedaling mode. CONCLUSIONS: The superiority of forced smooth cycling to free cycling, as regards functional output distance, is based on less energy expenditure (less jerk loss and muscle tension) and on more efficient production of energy (more efficient timing and joint location of work production). Some energetic mechanisms that are advantageous for fixed-gear cycling act predominantly in unsteady phases; others work continuously during all phases of cycling.     

Effects of hamstring‐emphasized neuromuscular training on strength and sprinting mechanics in football players

The objective of this study was to examine the effects of a neuromuscular training program combining eccentric hamstring muscle strength, plyometrics, and free/resisted sprinting exercises on knee extensor/flexor muscle strength, sprinting performance, and horizontal mechanical properties of sprint running in football (soccer) players. Sixty footballers were randomly assigned to an experimental group (EG) or a control group (CG). Twenty‐seven players completed the EG and 24 players the CG. Both groups performed regular football training while the EG performed also a neuromuscular training during a 7‐week period. The EG showed a small increases in concentric quadriceps strength (ES = 0.38/0.58), a moderate to large increase in concentric (ES = 0.70/0.74) and eccentric (ES = 0.66/0.87) hamstring strength, and a small improvement in 5‐m sprint performance (ES = 0.32). By contrast, the CG presented lower magnitude changes in quadriceps (ES = 0.04/0.29) and hamstring (ES = 0.27/0.34) concentric muscle strength and no changes in hamstring eccentric muscle strength (ES = ?0.02/0.11). Thus, in contrast to the CG (ES = ?0.27/0.14), the EG showed an almost certain increase in the hamstring/quadriceps strength functional ratio (ES = 0.32/0.75). Moreover, the CG showed small magnitude impairments in sprinting performance (ES = ?0.35/?0.11). Horizontal mechanical properties of sprint running remained typically unchanged in both groups. These results indicate that a neuromuscular training program can induce positive hamstring strength and maintain sprinting performance, which might help in preventing hamstring strains in football players.     

Increase in muscle tone promotes the use of ankle strategies during perturbed stance

Background:To maintain an upright standing posture against external disturbances, the human body mainly employs two types of postural control strategies: “ankle strategy” and “hip strategy.” While it has been reported that the magnitude of the disturbance alters the use of postural control strategies, it has not been elucidated how the level of muscle tone, one of the crucial parameters of bodily function, determines the use of each strategy. We have previously confirmed using forward dynamics simulations of human musculoskeletal models that an increased muscle tone promotes the use of ankle strategies. The objective of the present study was to experimentally evaluate a hypothesis: an increased muscle tone promotes the use of ankle strategies.Research question:Do changes in the muscle tone affect the use of ankle strategies?Methods:Participants were asked to maintain their standing posture on a movable platform sliding horizontally at several accelerations. Postural reactions for support surface translations were examined under three instructions with or without handgrips: relax state, squeezing a handgrip, and an increased muscle tone of the whole body. Surface-electromyography and marker locations of joints were measured to calculate the index of muscle tone and postural control strategies. The relationship of the indexes was evaluated based on correlation coefficients.Results:In half of the conditions, weak negative correlations were noted between the muscle tone index and postural control strategy index. In other words, an increased muscle tone rather promoted the use of the ankle strategy than the hip strategy. These findings are consistent with our previous simulation results.Significance:The results recognized a positive response to the research question. This suggests that it is crucial to take muscle tone into account to understand postural control strategies.     

Promoting balance and strength in the middle-aged workforce

The prevalence of sustaining fall-related injuries is high in the middle-aged workforce. Deficits in postural control/muscle strength represent important fall-risk factors. The objective of this study was to examine the impact of balance and strength training followed by detraining on postural control and muscle strength in the workforce. Thirty-two adults with sedentary office work participated in this study and were assigned to an intervention (age 56.0 ± 3.7 yrs) or a control group (age 55.5 ± 3.4 yrs). The intervention group participated in 8 weeks of balance and strength training conducted at the worksite, followed by 8 weeks of detraining. Tests included the measurement of (a) total centre of pressure (COP) displacements during one-legged standing, (b) gait velocity and stride-to-stride variability, (c) peak isometric/isokinetic torque and rate of torque development (RTD) of the plantar flexors, and (d) jumping height. After training, significant improvements in COP displacements, gait velocity, peak isometric/isokinetic torque, RTD, and jumping height were observed. During detraining, muscle strength deteriorated, whereas postural control improved. This fall-preventive training program conducted at the worksite proved to be feasible and effective. It is suggested that this training program should be permanently conducted to maintain/improve muscle strength.     

Postural balance asymmetry and subsequent noncontact lower extremity musculoskeletal injuries among Tunisian soccer players with groin pain: A prospective case control study

BackgroundRecent studies reported postural balance disorders in patients and soccer players with groin pain (GP) compared to controls. Since postural balance asymmetry identified after an initial injury contributes for subsequent injuries, identification of this asymmetry in soccer players with GP may highlight the risk of sustaining subsequent noncontact lower extremity musculoskeletal injuries in these players. Therefore, the aims of this study were to (i) examine static and dynamic unipedal postural balance asymmetry in soccer players with GP compared to healthy ones, and (ii) quantify the risk of subsequent noncontact lower extremity injuries in these players.Research questionDo soccer players with GP exhibit higher static and dynamic unipedal postural balance asymmetry, and higher risk of sustaining subsequent injuries compared to controls?MethodsIn this prospective case control study, 27 soccer players with non-time loss GP (GP group: GPG), and 27 healthy ones (control group: CG) were enrolled. Static and dynamic unipedal postural balance asymmetry were evaluated with a force platform using symmetry index (SI), and Y-balance test (Y-BT), respectively. Additionally, subsequent noncontact lower extremity musculoskeletal injuries were tracked for 10 months.ResultsThe GPG revealed higher (p < 0.01) SI in eyes closed condition, higher (p < 0.001) side-to-side asymmetry in anterior, posteromedial and posterolateral reach distances and in composite Y-BT score compared to CG. They showed lower (p < 0.001) composite score for injured limb and higher (p < 0.001) side-to-side asymmetry in posteromedial reach distance compared to the cut-off values of 89.6 % and 4 cm, respectively. Moreover, GPG exhibited higher odds (OR= 7.48; 95 % CI = 2.15, 26.00; p < 0.01) of sustaining subsequent injuries compared to CG.SignificanceThe Y-BT should be instituted into existing pre-participation physical examinations to screen for soccer players with non-time loss GP at an elevated risk of sustaining subsequent injuries. This could help coaches and clinicians make valid return to play decisions.     

Insulin action and long-term electrically induced training in individuals with spinal cord injuries

PURPOSE: Individuals with spinal cord injuries (SCI) have an increased prevalence of insulin resistance and type 2 diabetes mellitus. In able-bodied individuals, training with large muscle groups increases insulin sensitivity and may prevent type 2 diabetes mellitus. However, individuals with SCI cannot voluntarily recruit major muscle groups, but by functional electrical stimulation (FES) they can now perform ergometer bicycle training. METHODS: Ten subjects with SCI (35 +/- 2 yr (mean +/- SE), 73 +/- 5 kg, level of lesion C6--Th4, time since injury: 12 +/- 2 yr) performed 1 yr of FES cycling (30 min x d(-1), 3 d x wk(-1) (intensive training)). Seven subjects continued 6 months with reduced training (1 d x wk(-1) (reduced training)). A sequential, hyperinsulinemic (50 mU x min(-1) x m(-2) (step 1) and 480 mU x min(-1) x m(-2) (step 2)), euglycemic clamp, an oral glucose tolerance test (OGTT), and determination of GLUT 4 transporter protein in muscle biopsies were performed before and after training. RESULTS: Insulin-stimulated glucose uptake rates increased after intensive training (from 4.9 +/- 0.5 mg x min(-1) x kg(-1) to 6.2 +/- 0.6 mg x min(-1) x kg(-1) (P < 0.008) (step 1) and from 9.0 +/- 0.8 mg x min(-1) x kg(-1) to 10.6 +/- 0.8 mg x min(-1) x kg(-1) (P = 0.103) (step 2)). With the reduction in training, insulin sensitivity decreased to a similar level as before training (P > 0.05). GLUT 4 increased by 105% after intense training and decreased again with the training reduction. The subjects had impaired glucose tolerance before and after training, and neither glucose tolerance nor insulin responses to OGTT were significantly altered by training. CONCLUSIONS: Electrically induced bicycle training, performed three times per week increases insulin sensitivity and GLUT 4 content in skeletal muscle in subjects with SCI. A reduction in training to once per week is not sufficient to maintain these effects. FES training may have a role in the prevention of the insulin resistance syndrome in persons with SCI.     

The effect of muscle actions on the level of connective tissue damage

The aim of this study was to compare the effect of concentric with eccentric muscle actions on the resulting level of damage to connective tissues by urinary concentration of hydroxyproline. Twenty-one male volunteers were divided into control group (CG), experimental concentric group (ECG), and experimental eccentric group (EEG). The measures of hydroxyproline were performed at three times: pretest, fourth week, and posttest. Biceps curl and chest press exercises also were performed with three sets of 10 repetitions two times per week for both experimental groups. Analysis of variance (ANOVA) showed a significant difference between pretest of the CG and pretest of the ECG (p = 0.002), and between pretest and posttest for the EEG (p = 0.029). Therefore, this study concluded that the level of damage to the connective tissue is greater when exercises involving eccentric muscle actions are performed. The continuity of training, however might reduce this damage.     

Acute ischemic stroke: predictive value of 2D phase-contrast MR angiography--serial study with combined diffusion and perfusion MR imaging

PURPOSE: To evaluate phase-contrast magnetic resonance (MR) angiography and diffusion- and perfusion-weighted imaging in predicting evolution of infarction and clinical outcome. MATERIALS AND METHODS: Phase-contrast angiographic and diffusion-weighted images obtained 1 and 2 days after acute middle cerebral artery (MCA) stroke were assessed in 43 patients; 39 underwent perfusion-weighted imaging on day 1. Follow-up phase-contrast angiographic and T2-weighted images (n = 38) were obtained on day 8. Clinical outcome was assessed at 3 months. Patients were assigned to three groups according to angiographic findings on day 1: group 1, absence of flow in proximal MCA (M1 segment); group 2, internal carotid artery (ICA) occlusion with collateral M1 flow; group 3, flow in ICA and M1. Differences in lesion volumes on diffusion- and perfusion-weighted maps among groups were compared with one-way analysis of variance with Tukey post hoc multiple comparisons. RESULTS: Patients in group 1 had significantly larger infarct growth, volumes of hypoperfusion on relative cerebral blood volume (rCBV) and relative cerebral blood flow maps, and initial and final infarct volumes than did other patients (P <.05). Initial perfusion deficits on mean transit time maps were significantly (P =.002) larger in group 2 than in group 3, but there were no significant differences in infarct growth (P =.977), final infarct volume on day 8 (P =.947), and clinical outcome (P =.969). Absence of M1 flow on day 1 was significantly associated with unfavorable clinical outcome (modified Rankin score > or = 3) at 3 months (P =.010, chi(2) test). Discriminant analysis revealed that rCBV maps alone and combination of diffusion-weighted imaging and MR angiography yielded the highest accuracy in predicting an unfavorable clinical outcome. CONCLUSION: Phase-contrast MR angiography can provide complementary information to that with diffusion- and perfusion- weighted imaging in predicting the outcome of patients with acute stroke.     

The effects of prior cycling and a successive run on respiratory muscle performance in triathletes

The aim of the present study was to compare the effects of prior cycling and a successive run on respiratory muscle performance during a cycle-run succession as performed in the triathlon. We hypothesized that despite the moderate intensity of exercise and the absence of exhaustion, the crouched cycling position would induce a decrease in respiratory muscle performance that would be reversed by the successive vertical run position. Ten male triathletes (22.6 +/- 1.1 yr) performed a four-trial protocol: (1) an incremental cycle test to assess maximal oxygen uptake (VO2max), (2) 20 min of cycling (C), (3) 20 min of running (R), and (4) 20 min of cycling followed by 20 min of running (C-R). Trials 2, 3 and 4 were performed at the same metabolic intensity, i. e., 75 % of VO2max. Respiratory muscle force was assessed by measuring maximal expiratory (P(Emax)) and inspiratory (P(Imax)) pressures from the functional residual capacity (FRC) before and 10 min after C, R, and C-R. Respiratory muscle endurance was assessed one day before and 30 min after C, R, and C-R, by measuring the time limit (T(lim)), which corresponds to the length of time a respiratory load can be sustained before the process of fatigue develops sufficiently to cause task failure. The results showed a similar significant decrease in P(Imax) (132.4 +/- 4.9 versus 125.7 +/- 5.6 cm H2O, p < 0.05) and T(lim) (5.22 +/- 0.28 versus 3.68 +/- 0.32 min, p < 0.05) post-C and post-C-R (133.7 +/- 4.0 versus 126.9 +/- 5.2 cm H2O, and 5.29 +/- 0.18 versus 3.49 +/- 0.41 min, respectively, p < 0.05) compared with the pre-trial values. In contrast, P(Imax) and T(lim) were not significantly decreased post-R (131.8 +/- 6.1 cm H2O versus 129.6 +/- 6.4 cm H2O, and 4.90 +/- 0.69 versus 4.40 +/- 0.56 min, respectively, p > 0.05). We concluded that moderate intensity exercise not performed to exhaustion induced a decrease in respiratory muscle performance. Moreover, the respiratory muscle fatigue induced by prior cycling was maintained, and neither reversed nor worsened, by the successive run.     

The influence of training on endurance and blood lactate concentration during submaximal exercise.

The purpose of this study was to examine the effect of short-term training on maximum oxygen uptake (VO2 max) and two different measures of endurance performance. Endurance was determined for 15 female subjects (7 training, 8 control) as (1) exercise time to exhaustion at 80% VO2 max (T80%) and (2) the highest relative exercise intensity tolerable during a 30-minute test (T30 min), before and after a 6-week training period. In addition, VO2 max and the work rate equivalent to a blood lactate concentration of 4 mmol.l-1 (OBLA) were determined. Maximum oxygen uptake increased by 24% (p less than 0.01) for the training group (TG) and 7% (p less than 0.01) for the control group (CG). Cumulative average work rate (CAWR) during T30 min increased by 25% for the TG while there was no change for the CG. No significant difference was found pre- and post-training in the %VO2 max (estimated from CAWR) at which the TG and CG performed T30 min. Exercise time to exhaustion on T80% increased by 347% (p less than 0.01) and 16% (NS) for the TG and the CG respectively. Good correlations were found between VO2 max and CAWR (W) (pre-training r = 0.84; post-training r = 0.83), OBLA (W) and CAWR (W) (pre-training r = 0.89; post-training r = 0.88) and change in endurance time and the change in submaximal blood lactate concentration (r = 0.70, p less than 0.01). The results of this study suggest that the ability to sustain a high relative exercise intensity is not enhanced following short-term training.     

Effect of training on postural control in figure skaters: a randomized controlled trial of neuromuscular versus basic off-ice training programs.

OBJECTIVES: To compare the effect of a neuromuscular training program and a basic exercise program on postural control in figure skaters. DESIGN: Two groups; parallel design; prospective, randomized controlled trial. SETTING: Postural control laboratory, arenas, September 2001 to December 2002. PARTICIPANTS: Forty-four young, healthy figure skaters (18 years +/- 3 years). INTERVENTIONS: Participants were randomly assigned to receive a neuromuscular training program (n = 22) or a basic exercise training program (n = 22). Both programs were completed 3 times per week for 4 weeks, and each session was supervised. MAIN OUTCOME MEASUREMENTS: Participants completed baseline and postintervention measures of postural control on a force plate. Postural control was quantified as the center of pressure (CoP) path length during tests of single-limb standing balance that mimicked figure skating skills and challenged the postural control system to varying degrees. The primary outcome measure was the CoP path length observed during a landing jump test completed with eyes closed. RESULTS: The post intervention CoP path lengths during the more challenging tests were significantly (P < 0.05) lower (indicating better postural control) for the neuromuscular trained group than for the basic exercise-trained group. For the landing jump test completed with eyes closed, the percent improvement in the neuromuscular trained group was significantly greater (mean = 21.0 +/- 22.0%) than the basic exercise trained group (mean = -4.9 +/- 24.9%; P < 0.05). The magnitude of improvement in the neuromuscular-trained group ranged from approximately 1% to 21%, depending on the specific postural control test used. CONCLUSIONS: The results suggest that off-ice neuromuscular training can significantly improve postural control in figure skaters, whereas basic exercise training does not.     

Effect of coordination training with and without stochastic resonance stimulation on dynamic postural stability of subjects with functional ankle instability and subjects with stable ankles.

OBJECTIVE: To examine the effects of coordination training with and without stochastic resonance (SR) stimulation on dynamic postural stability. DESIGN: Experimental with repeated measures. SETTING: Research Laboratory. PARTICIPANTS: Thirty subjects with functional ankle instability (FAI) and 30 healthy subjects. INTERVENTIONS: Subjects were assigned to a conventional coordination training group, SR stimulation coordination training group, or control group. Training groups performed coordination exercises for 6 weeks. Single leg jump-landing tests were performed before training began (pretest), and then once every 2 weeks. Jump-landing tests required subjects to land on a single leg on a force plate and stabilize quickly. MAIN OUTCOME MEASURES: Anterior/posterior (A/P) and medial/lateral (M/L) time-to-stabilization (TTS). RESULTS: The FAI group improved their A/P TTS over their pretest by 16% (test 2), 22% (test 3), and 22% (posttest). They also improved their M/L TTS over their pretest by 16% (test 3) and 22% (posttest). Control groups did not improve their TTS (P>0.05). SR stimulation did not statistically influence TTS (P>0.05). Effect sizes (ES), however, for our 3-way interaction analyses for A/P TTS (ES=0.40) and M/L TTS (ES=0.30) suggested that SR stimulation improved the FAI group's M/L TTS after 2 weeks of training, and improved their A/P TTS and M/L TTS to a greater degree after 4 weeks than coordination training alone. CONCLUSION: Coordination training can improve dynamic postural instabilities associated with FAI. SR stimulation might be an alternative therapy for FAI, as this stimulation might improve dynamic postural stability more quickly and to a greater extent than coordination training without SR stimulation.