Noise-enhanced postural stability in subjects with functional ankle instability

Objective

To examine the effects of stochastic resonance (SR) stimulation on the postural stability of subjects with functional ankle instability (FAI).

Design

Experimental research design.

Setting

Sports medicine research laboratory.

Participants

12 subjects with FAI who reported a history of recurrent ankle sprains and “giving way” sensations at the ankle.

Interventions

Subjects performed 20 s single‐leg balance tests under SR stimulation at 0.05 mA and 0.01 mA and under control conditions. Testing order was randomised. Stimulators that delivered subsensory stimulation to ankle muscles and ligaments were worn. Subjects were blinded to the test conditions, as SR stimulation was subsensory and stimulators were turned off during the control condition.

Main outcome measures

Anterior/posterior and medial/lateral centre‐of‐pressure velocities (COPVs) were combined to form a resultant vector (COPV‐R). The COPV‐R differences between the optimal SR stimulation and control conditions were analysed. Optimal SR stimulation was defined as the SR stimulation input intensity level (0.05 mA or 0.01 mA) that produced the greatest percentage improvement in postural stability compared with the control condition. Slower velocities indicated enhanced postural stability.

Results

The optimal input intensity was 0.05 mA for nine subjects and 0.01 mA for the other three. The optimal SR stimulation significantly (p<0.05) improved COPV‐R compared with the control condition (6.60 (1.06) vs 7.20 (1.03) cm/s; mean (SD)).

Conclusion

SR stimulation may enhance signal detection of sensorimotor signals associated with postural stability. This result has clinical relevance as improvements in postural instability associated with FAI may decrease ankle sprain injury.     

Detection of dynamic stability deficits in subjects with functional ankle instability

PURPOSE: To determine which combination of landing protocol and analysis technique would be the most effective at detecting differences in dynamic stability between healthy subjects and subjects with functional ankle instability (FAI). METHODS: Fifty-eight subjects participated in this investigation: 29 healthy individuals and 29 individuals with FAI. Subjects were assessed during a single test session for time to stabilization (TTS) in the anterior/posterior, medial/lateral, and vertical directions from two protocols: a step down and jump protocol. The step down protocol started with each subject atop a 20-cm-high platform, and the jump protocol started with subjects in a standing position 70 cm from the center of a force plate and required each subject to jump off both legs and touch a designated marker placed at a position equivalent to 50% of the subject's maximum vertical leap. TTS scores in the anterior/posterior, medial/lateral, and vertical direction were compared between group, protocol, and type of analysis. RESULTS: A significant protocol by analysis by group interaction (F(1,56) = 6.9, P = 0.011) was observed for anterior/posterior TTS. Likewise, protocol by group (F(1,56) = 4.4, P = 0.042) and protocol by analysis (F(1,56) = 14.1, P < 0.001) interactions were also noted in anterior/posterior TTS. The jump protocol (2381.7 +/- 36.5 ms) produced significantly greater TTS scores in the vertical direction than the step protocol (1533.5 +/- 71.8 ms), whereas the unbounded third order polynomial (UTOP) method (2554.4 +/- 68.7 ms) produced significant greater TTS scores as compared with the sequential estimation (SE) method (1360.8 +/- 52.1 ms). CONCLUSIONS: The jump protocol and UTOP method of analysis are the most effective TTS combination in detecting differences between healthy and FAI groups.     

Dynamic postural stability deficits in subjects with self-reported ankle instability

PURPOSE: A limited understanding of how functional ankle instability (FAI) affects dynamic postural stability exists because of a lack of reliable and valid measures. Therefore, the purpose of this investigation was to determine whether a new reliable index for dynamic postural stability could differentiate between those with stable ankles and those with FAI. METHODS: Data were collected on 108 subjects (54 subjects with stable ankles (STABLE group); 54 subjects with functionally unstable ankles (FAI group)). Subjects performed a single-leg-hop stabilization maneuver in which they stood 70 cm from the center of a force plate, jumped off both legs, touched a designated marker placed at a height equivalent to 50% of their maximum vertical leap, and landed on a single leg. The dynamic postural stability index and directional stability indices (medial/lateral, anterior/posterior, and vertical) were calculated. The raw and normalized (to energy dissipated) indices were compared between groups. RESULTS: Significant differences were noted for the anterior/posterior stability index (FAI = 0.36 +/- 0.09, STABLE = 0.30 +/- 0.06). Similar results were seen for the vertical stability index (FAI = 0.73 +/- 0.17, STABLE = 0.61 +/- 0.13), the normalized dynamic postural stability index (FAI = 0.85 +/- 0.17, STABLE = 0.73 +/- 0.12), the normalized vertical stability index (FAI = 0.007 +/- 0.004, STABLE = 0.005 +/- 0.001), and the dynamic postural stability index (FAI = 0.008 +/- 0.003, STABLE = 0.006 +/- 0.001). CONCLUSIONS: These results indicate that the dynamic postural stability index is a sensitive measure of dynamic postural stability and is capable of detecting differences between individuals with stable ankles and individuals with functionally unstable ankles.     

Effect of Kinesio taping on Y-balance test performance and the associated leg muscle activation patterns in children with developmental coordination disorder: A randomized controlled trial

BackgroundChildren with developmental coordination disorder (DCD) have leg muscular deficits which negatively affects their dynamic postural stability. Kinesio tape (KT) could enhance muscle activation, postural control and functional activities in healthy individuals. Therefore, we hypothesized that the usage of KT may address the postural instability problem of children with DCD.Research questionTo investigate the immediate effect of KT on dynamic postural stability and the associated lower limb muscle activity in children with DCD.MethodsForty-nine children with DCD were recruited where twenty-five children were randomly assigned to the KT group (mean age = 8.18 ± 1.16 years) and twenty-four to the control group (mean age = 8.06 ± 0.93 years). KT group received KT application to the rectus femoris and gastrocnemius muscles whereas the control group received no intervention. Measurements were taken before and after the application of KT. Dynamic balance performance was measured using a lower quartile Y-balance test (YBT-LQ). Leg muscle peak activation and time-to-peak muscle activation of the dominant lower limb during YBT-LQ were measured by surface electromyography.ResultsYBT-LQ composite score increased by 6.3% in the KT group at posttest (95% CI: -7.308, -2.480). In addition, a higher rectus femoris peak activation was illustrated for YBT-LQ anterior (32.5%; 95% CI: -48.619, -16.395) and posteromedial (24.6%; 95% CI: -42.631, -6.591) reach directions from pretest values in the KT group. Moreover, KT group exhibited a 38% (95% CI: 0.015, 2.983) longer gastrocnemius medialis time-to-peak duration for YBT-LQ posteromedial reach direction when compared to the control group.SignificanceKT revealed an immediate beneficial effect on YBT-LQ performance. Application of KT also increased rectus femoris peak activation and lengthened the muscle time-to-peak duration for specific reach directions. Incorporating KT as an adjunct with dynamic balance training programme could be beneficial for children with DCD.     

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.     

Cycling exercise with functional electrical stimulation improves postural control in stroke patients

The aim of this study is to determine whether short term functional electrical stimulation (FES)-assisted cycling training can affect the postural control of stroke patients, and whether the application of FES can enhance the effect of cycling training. 20 stroke patients were randomly assigned to the FES-cycling group (FES-CG) or the cycling group (CG). Measurements were completed before and immediately after each 20 min training sessions. The measurements included a balance test (to quantify the postural control ability), a Hoffmann's reflex/motor response ratio (H/M ratio) test and a pendulum test (to quantify the muscle tone). In the balance test, some parameters in all directions exhibited significant intervention effects between the FES-CG group and the CG group. The H/M ratios (p=.014; .005, FES-CG and CG respectively) and relaxation index (p=.005; .047, FES-CG and CG respectively) revealed significant difference between FES-CG and CG group. The change ratios of directional control in the forward direction and H/M ratio revealed significant difference (p=.022; .015) between FES-CG and CG among subjects with higher muscle tone. The stroke subjects' postural control was improved while their muscle tone was reduced after the 20 min cycling training program both with and without FES. We conclude that cycling training, with or without FES may reduce spasticity in stroke patients. The application of FES in cycling exercise was shown to be more effective in stroke patients with higher muscle tone.     

Alternative foot placements for individuals with spinal cord injuries standing with the assistance of functional neuromuscular stimulation

This study investigated the effects of altering foot placement for two individuals with spinal cord injuries (SCI) that stood using functional neuromuscular stimulation (FNS) as compared to an able-bodied subject group. FNS-assisted standers used parallel bars as needed for support, while the able-bodied group stood hands-free. Three different foot placements were tested: side-by-side, wide, and modified tandem. For SCI subjects, the percentage of body weight loaded on the feet was not greatly affected by foot placement, which potentially could be altered to provide postural benefits during functional tasks. Anterior/posterior (A/P) center of pressure (COP) origins tended to be located more anterior in the base of support for SCI subjects as compared to able-bodied subjects. SCI subjects also tended to have medial/lateral (M/L) COP excursions that were larger than able-bodied subjects. The sacrum appeared to hold some promise as a sensor location for monitoring A/P postural sway, but movements in the M/L direction were inconsistent and will require additional study. General guidelines such as positioning the A/P COP more posterior in the base of support and feedback concerning excessive M/L COP displacements may be useful to improve standing performance for SCI subjects. In addition, the modified tandem placement was an effective alternative for making postural adjustments in one SCI subject who experienced excessive right knee flexion with other foot placements.     

Metabolism and performance in repeated cycle sprints: active versus passive recovery

PURPOSE: To compare active versus passive recovery on performance and metabolism during a test of repeated-sprint ability. METHODS: Nine males performed four repeated-sprint cycle tests (six 4-s sprints, every 25 s) in a randomized, counterbalanced order: two tests with active recovery (approximately 32% VO2max) and two with passive recovery. Muscle biopsies were taken during the four tests from the vastus lateralis pretest, immediately posttest, and following 21 s of recovery to determine phosphocreatine ([PCr]), creatine, and muscle lactate concentration ([MLa]). RESULTS: Active recovery resulted in a greater power decrement than passive recovery (7.4 +/- 2.2 vs 5.6 +/- 1.8%, P = 0.01) and lower final peak power (14.9 +/- 1.5 vs 15.3 +/- 1.5 W.kg(-1), P = 0.02). However, there was no significant difference in work decrement or total work. The percent of resting [PCr] was lower and approached significance posttest (32.6 +/- 10.6 vs 45.3 +/- 18.6%; P = 0.06; effect size (ES) = 0.8) and following 21 s of recovery (54.6 +/- 9.6 vs 71.7 +/- 14.1%; P = 0.06; ES = 1.2) during active recovery. The [MLa] was significantly higher posttest during active recovery (71.7 +/- 12.3 vs 55.2 +/- 15.7 mmol.kg(-1)dm; P = 0.048; ES = 1.2); however, no significant differences were evident following 21 s of recovery (55.0 +/- 11.3 vs 48.4 +/- 16.7 mmol.kg(-1)dm, P = 0.07; ES = 0.5). CONCLUSIONS: Despite no differences in the majority of performance measures, active recovery resulted in a significantly lower final peak power, a greater peak power decrement, a higher [MLa], and a strong trend towards lower [PCr], suggesting a potential suboptimal effect of active recovery during repeated-sprint exercise.     

No effect of dietary nitrate supplementation on endurance training in hypoxia

We investigated whether dietary nitrate (NO₃^?) supplementation enhances the effect of training in hypoxia on endurance performance at sea level. Twenty‐two healthy male volunteers performed high‐intensity endurance training on a cycle ergometer (6 weeks, 5×30 min/week at 4–6 mmol/L blood lactate) in normobaric hypoxia (12.5% FiO₂), while ingesting either beetroot juice [0.07 mmol NO₃^?/kg body weight (bw)/day; BR, n = 11] or a control drink (CON, n = 11). During the pretest and the posttest, the subjects performed a 30‐min simulated time trial (TT) and an incremental VO_2max test. Furthermore, a biopsy was taken from m. vastus lateralis before and after the TT. Power output during the training sessions in both groups increased by ～6% from week 1 to week 6 (P < 0.05). Compared with the pretest, VO_2max in the posttest was increased (P < 0.05) in CON (5%) and BR (9%). Power output corresponding with the 4 mmol/L blood lactate threshold, as well as mean power output during TT increased by ～16% in both groups (P < 0.05). Muscle phospho‐AMP‐activated protein kinase, hypoxia inducible factor‐1α mRNA content, and glycogen breakdown during the TT were similar between the groups in both the pretest and the posttest. In conclusion, low‐dose dietary NO₃^? supplementation does not enhance the effects of intermittent hypoxic training on endurance exercise performance at sea level.     

Acute effects of intense interval versus aerobic exercise on children's behavioral and neuroelectric measures of inhibitory control

ObjectivesDetermine the acute effect of high-intensity interval training as an alternative of moderate-intensity aerobic exercise on behavioral and neuroelectric measures of inhibitory control in preadolescent children.DesignA randomized controlled trial.MethodsSeventy-seven children (8–10 years) were randomly assigned to three groups to complete a modified flanker task to measure behavioral and neuroelectric (N2/P3 of event-related potential and frontal theta oscillations) outcomes of inhibitory control before and after a 20-min session of high-intensity interval training (N = 27), moderate-intensity aerobic exercise (N = 25), and sedentary reading activity (N = 25).ResultsThe accuracy of the inhibitory control performance improved over time across three groups but response time was selectively improved only for the high-intensity interval training group. Analysis on N2 showed a time-related decrease in N2 latency selectively for the high-intensity interval training but not the other groups. Analysis on P3 showed a time-related decrease in P3 amplitude for the sedentary and high-intensity interval training groups while the moderate-intensity aerobic exercise group exhibited maintained P3 amplitude from the pretest to the posttest and a larger P3 amplitude compared with the high-intensity interval training group at the posttest. While there was evidence of conflict-induced modulation of frontal theta oscillations, such an effect was unaffected by exercise interventions.ConclusionsA single bout of high-intensity interval training has facilitating effects on the processing speed involving inhibitory control in preadolescent children but not neuroelectric index of attention allocation that only benefited from moderate-intensity aerobic exercise.     

Effects of balance training with visual feedback during mechanically unperturbed standing on postural corrective responses

Evidence of a non-specific effect of balance training on postural control mechanisms suggests that balance training during mechanically unperturbed standing may improve postural corrective responses following external perturbations. The purpose of the present study was to examine kinematics of the trunk as well as muscular activity of the lower leg and paraspinal muscles during postural responses to support-surface rotations after short-term balance training. Experiments were performed in control (n=10) and experimental (n=11) groups. The experimental group participated in the 3-day balance training program. During the training, participants stood on a force platform and were instructed to voluntarily shift their center of pressure in indicated directions as represented by a cursor on a monitor. Postural perturbation tests were executed before and after the training period: the slow and fast 10° dorsiflexions were induced at angular velocities of approximately 50°s(-1) and 200°s(-1), respectively. In the experimental group, the amplitude of the trunk displacements during slow and fast perturbations was up to 33.4% and 26.7% lower, respectively, following the training. The magnitude of the muscular activity was reduced in both the early and late components of the response. The kinematic parameters and muscular responses did not change in the control group. The results suggest that balance training during unperturbed standing has the potential to improve postural corrective responses to unexpected balance perturbation through (1) improved neuromuscular coordination of the involved muscles and (2) adaptive neural modifications on the spinal and cortical levels facilitated by voluntary activity.     

Medical students and radiology residents: can they learn as effectively with the same educational materials?

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the effectiveness of resident-prepared, independent-learning materials for teaching chest radiology to medical students. MATERIALS AND METHODS: Students from three U.S. medical schools enrolled in radiology clerkships between March 1998 and June 1998 were randomly divided into control (n = 27) and experimental (n = 31) groups. The experimental group studied 12 chest radiology independent-learning cases (intervention) used to teach radiology residents in a previous study. Both groups took a 36-item, multiple-choice test (previously used to test radiology residents) on three occasions (before intervention [pretest], 1 day after intervention [posttest], and 2-4 weeks after intervention [final examination]). Student scores were then compared with resident scores. RESULTS: Mean scores were similar across institutions at pretest, but increases at posttest and final examination scores differed across time, school, and group (P < .005). Mean differences in scores between experimental and control groups at pretest, posttest, and 2-4-week final examination were -0.22, 9.79, and 9.14, respectively, demonstrating increased performance at posttesting that remained present (though slightly attenuated) 2-4 weeks later. Comparing performance, residents had mean pretest scores of 19.2 and students of 14.1, a five-point difference attributable to the residents' greater experience. Both residents and students gained approximately nine points at posttest. At final examination, the difference between residents and students was only 1.4 points, suggesting the experimental program (teaching materials) brought students close to the long-term retention shown by residents. CONCLUSION: Independent study of resident-prepared chest radiology teaching cases increased medical student knowledge for at least 2 or 4 weeks after instruction. Although starting at lower knowledge levels, students experienced gains in knowledge comparable to those of residents, suggesting the same materials can be used to teach both students and residents.     

Block periodization of high‐intensity aerobic intervals provides superior training effects in trained cyclists

The purpose of this study was to compare the effect of two different methods of organizing endurance training in trained cyclists. One group of cyclists performed block periodization, wherein the first week constituted five sessions of high‐intensity aerobic training (HIT), followed by 3 weeks of one weekly HIT session and focus on low‐intensity training (LIT) (BP; n = 10, VO_2max = 62 ± 2 mL/kg/min). Another group of cyclists performed a more traditional organization, with 4 weeks of two weekly HIT sessions interspersed with LIT (TRAD; n = 9, VO_2max = 63 ± 2 mL/kg/min). Similar volumes of both HIT and LIT was performed in the two groups. While BP increased VO_2max, peak power output (W_max) and power output at 2 mmol/L [la^?] by 4.6 ± 3.7%, 2.1 ± 2.8%, and 10 ± 12%, respectively (P < 0.05), no changes occurred in TRAD. BP showed relative improvements in VO_2max compared with TRAD (P < 0.05). Mean effect size (ES) of the relative improvement in VO_2max, W_max, and power output at 2 mmol/L [la^?] revealed large to moderate effects of BP training compared with TRAD training (ES = 1.34, ES = 0.85, and ES = 0.71, respectively). The present study suggests that block periodization of training provides superior adaptations to traditional organization during a 4‐week endurance training period, despite similar training volume and intensity.     

Effects of jump training with negative versus positive loading on jumping mechanics

We examined the effects of jump training with negative (-30% of the subject's body weight (BW)) VS. positive loading (+30% BW) on the mechanical behaviour of leg extensor muscles. 32 men were divided into control (CG), negative loading (NLG), or positive loading training group (PLG). Both training groups performed maximal effort countermovement jumps (CMJ) over a 7-week training period. The impact of training on the mechanical behaviour of leg extensor muscles was assessed through CMJ performed with external loads ranging from -30% BW to +30% BW. Both training groups showed significant ( P≤0.013) increase in BW CMJ height (NLG: 9%, effect size (ES)=0.85, VS. PLG: 3.4%, ES=0.31), peak jumping velocity ( V(peak); NLG: 4.1%; ES=0.80, P=0.011, VS. PLG: 1.4%, ES=0.24; P=0.017), and depth of the countermovement (Δ H(ecc); NLG: 20%; ES=-1.64, P=0.004, VS. PLG: 11.4%; ES=-0.86, P=0.015). Although the increase in both the V(peak) and Δ H(ecc) were expected to reduce the recorded ground reaction force, the indices of force- and power-production characteristics of CMJ remained unchanged. Finally, NLG (but not PLG) suggested load-specific improvement in the movement kinematic and kinetic patterns. Overall, the observed results revealed a rather novel finding regarding the effectiveness of negative loading in enhancing CMJ performance which could be of potential importance for further development of routine training protocols. Although the involved biomechanical and neuromuscular mechanisms need further exploration, the improved performance could be partly based on an altered jumping pattern that utilizes an enhanced ability of leg extensors to provide kinetic and power output during the concentric jump phase.     

Visual feedback training improves postural adjustments associated with moving obstacle avoidance in elderly women

The study examined the impact of visually guided weight shifting (WS) practice on the postural adjustments evoked by elderly women when avoiding collision with a moving obstacle while standing. Fifty-six healthy elderly women (70.9+/-5.7 years, 87.5+/-9.6 kg) were randomly assigned into one of three groups: a group that completed 12 sessions (25 min, 3s/week) of WS practice in the Anterior/Posterior direction (A/P group, n=20), a group that performed the same practice in the medio/lateral direction (M/L group, n=20) and a control group (n=16). Pre- and post-training, participants were tested in a moving obstacle avoidance task. As a result of practice, postural response onset shifted closer to the time of collision with the obstacle. Side-to-side WS resulted in a reduction of the M/L sway amplitude and an increase of the trunk's velocity during avoidance. It is concluded that visually guided WS practice enhances elderly's ability for on-line visuo-motor processing when avoiding collision eliminating reliance on anticipatory scaling. Specifying the direction of WS seems to be critical for optimizing the transfer of training adaptations.     

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.     

Training potential of visual feedback to improve dynamic postural stability

BackgroundDeficits in single-limb dynamic postural stability are predictive for reinjuries of the lower extremities, which are very common in sports. The use of force plates has become increasingly common to measure dynamic postural stability. Visual feedback on force-plate based stability outcomes have been shown to improve performance during static tasks. A similar effect might occur in dynamic tasks. Since dynamic tasks are generally more specific for performance during sport, this could have important training implications.Research questionWhat is the effect of visual feedback on postural stability outcomes during a dynamic stability task?MethodsTwenty-four healthy participants participated in this study. During measurements, subjects were standing on one leg while mediolateral position-controlled platform perturbations were used to evoke and measure balance responses. All participants were tested under three conditions: with visual Time-to-Stability (TTS) feedback, with visual Center of Pressure speed (COPs) feedback and without visual feedback. TTS and COPs outcomes were calculated over a 5-second time window after each perturbation and were compared between conditions.ResultsVisual feedback resulted in significantly better stability outcomes during the dynamic stability task. TTS feedback resulted in a task-specific feedback learning effect, as it resulted in a gradual improvement of TTS scores (from 1.09 s to 0.68 s; −38%) in absence of a significant change in COPs. COPs feedback resulted in a non-specific attention effect, directly improving COPs (without feedback 5.26 cm/s with feedback 4.95 cm/s; −6%) and TTS scores (without feedback 1.47 s with feedback 0.99 s; −39%) in absence of an apparent further improvement over time.SignificanceThe ability to improve performance of dynamic stability tasks when visual feedback is added could have substantial impact for rehabilitation. Possibly, the use of visual feedback during stability training could improve the effectiveness of postural stability training.     

The effects of short term balance training on the postural control of older adults

The purpose of this study was to determine and contrast the effect of five weeks of balance training on the postural stability of elderly adults with a history of falls (F) and those who have not previously fallen (NF). Twelve F subjects, 12 NF subjects, and 14 control subjects participated. Balance training consisted of exercises designed to stress balance and coordination performed three times per week for five weeks. Postural stability was evaluated with an ADL test resembling activities of daily living and force-platform-based postural sway measurements. In general F and NF reflected similar improvements in postural stability following training. F and NF demonstrated small improvements (5–10%) on the ADL tests with respect to the control group. The postural sway measures provided only moderate support for the effectiveness of training, with the control subjects exhibiting improvements similar to those of the training groups (approximately 15–30%). Overall the data provide moderate support for the effectiveness of short term balance training for functionally independent elderly adults.     

Comparison of two abdominal training devices with an abdominal crunch using strength and EMG measurements

BACKGROUND: The purpose of this study was to compare the training effects of the Ab-Flex (F), Ab-Roller (R) and standard crunch (C) on EMG production, isometric maximum voluntary contraction (MVC), and isokinetic average peak torque at 30 degrees/sec (ISO) of the abdominal muscles. It was hypothesized that the training devices would have similar value in a strength training program. METHODS: Experimental design: this was a prospective study involving 18 training sessions of progressively increasing repetitions. Setting: Neuromuscular Research Laboratory, University of Pittsburgh. Subjects: thirty-two subjects volunteered for this study, but only 26 completed the training. Each subject participated in recreational activity, but had not performed any abdominal training prior to starting this study. Each subject was randomly assigned to either the control group or one of the treatment groups. Interventions: there were three interventions: two training devices (Ab-Flex and Ab-Roller) and the standard crunch, considered a control group. Measures: the pretest consisted of skin fold measurements (%), EMG activity (V) during the three interventions, and peak torque (Nm) plus EMG during the MVC and ISO tasks. The 18 training sessions over three weeks consisted of three sets of exercise with increasing repetitions from 10 to 20, by 2, every three sessions. The difference in pretest/posttest scores were compared using a One-way ANOVA on the mean differences (Mdiff) for each of: MVC, ISO (peak torque), and EMG for upper rectus (UR), lower rectus (LR), internal oblique (IO), and external oblique (EO). A T-Test was used to detect significance for the body fat measures. RESULTS: Mean differences (Mdiff) were normally distributed about zero for both MVC and ISO (MVC = -0.55, ISO = 4.57). The analysis by group showed no difference (p = 0.596) on the reported means (Nm) -3.16 (C), 5.84 (F) and -4.83 (R). The change associated to the treatment during MVC was only 4% (eta = 0.04). For the ISO the Mdiff (Nm) were 1.39 (C), 13.66 (F) and -2.06 (R) which were not significant (p = 0.127). The Ab-Flex was the only group to have a 95% confidence interval above zero, increasing by an average of 16.5%. There were no significant differences for the EMG activity for Mdiff or between group scores. CONCLUSIONS: No significant differences were found with this study. These results would suggest that using these devices does not add significantly to overall abdominal strength development, or reduction of body fat. A suggestion could be made that certain devices influence muscles differently.     

Effects of 12 weeks of block periodization on performance and performance indices in well‐trained cyclists

The purpose of this study was to compare the effects of two different methods of organizing endurance training in trained cyclists during a 12‐week preparation period. One group of cyclists performed block periodization (BP; n = 8), wherein every fourth week constituted five sessions of high‐intensity aerobic training (HIT), followed by 3 weeks of one HIT session. Another group performed a more traditional organization (TRAD; n = 7), with 12 weeks of two weekly HIT sessions. The HIT was interspersed with low‐intensity training (LIT) so that similar total volumes of both HIT and LIT were performed in the two groups. BP achieved a larger relative improvement in VO_2max than TRAD (8.8 ± 5.9% vs 3.7 ± 2.9%, respectively, P < 0.05) and a tendency toward larger increase in power output at 2 mmol/L [la^?] (22 ± 14% vs 10 ± 7%, respectively, P = 0.054). Mean effect size (ES) of the relative improvement in VO_2max, power output at 2 mmol/L [la^?], hemoglobin mass, and mean power output during 40‐min all‐out trial revealed moderate superior effects of BP compared with TRAD training (ES range was 0.62–1.12). The present study suggests that BP of endurance training has superior effects on several endurance and performance indices compared with TRAD.