Lower Body Positive Pressure Research Articles

Lower-Body Positive Pressure Treadmill Training for Pediatric Gait Disorders: A Scoping Review

The purpose of this scoping review was to examine the literature on the use of anti-gravity treadmills and its effects on lower-limb motor functions in children and adolescents with locomotor impairments. Method: Four databases (MEDLINE, CINAHL, Embase, Web of Science) were searched for articles from inception to August 2021. Inclusion criteria were: (1) experimental or quasi-experimental studies using anti-gravity training as the primary intervention; (2) studies conducted in pediatric participants; (3) articles reporting outcomes related to lower-limb functions; and (4) studies published in French or English. Results: Fifteen articles were included in the review. Studies included children and adolescents aged 4–18 years with locomotor impairments. Intervention duration ranged from 2 to 12 weeks, with 2–5 sessions per week. Included studies reported that anti-gravity training induces improvements in muscle strength, balance, spatiotemporal gait parameters, and walking endurance in children with locomotor impairments. Conclusion: This review provides relevant information about interventions, outcomes and limits associated with anti-gravity training in pediatrics. Overall, anti-gravity treadmill training could be viewed as a valuable training modality, specifically for children with cerebral palsy. However, a more precise and comprehensive description of anti-gravity training protocols would be useful.

Reliability of pain scores during a body weight support protocol in individuals with knee osteoarthritis

Purpose To explore the reliability of percentage of Body Weight Support (BWS) needed for maximal pain relief and of pain scores across 12 walking conditions including pre and post-over-ground walking and an unweighting protocol from 0% to 40% BWS on a lower body positive pressure (LBPP) treadmill for individuals with knee osteoarthritis (OA). Materials and methods Twenty individuals (64 ± 9.44 years) with knee OA completed over-ground walking and an unweighting protocol on an LBPP treadmill. The amount of BWS started at 0% and increased by 5% increments until it reached 40%. Pain scores were recorded at the end of each increment. Results The reliability of pain scores was assessed using a Spearman’s rho. This study found moderate reliability of the percentage of BWS for maximal pain relief. Additionally, there was good reliability of pain scores with pre and post-over-ground walking and from 0% BWS to 30% BWS, but moderate reliability of pain scores was found at 35% and 40% BWS. Conclusion This study supports the use of pain scores as a reliable measure during an unweighted walking session on an LBPP treadmill. IMPLICATIONS FOR REHABILITATION Both the OARSI and ACR recommend exercise in the treatment of individuals with knee OA but acknowledge that pain during exercise and exercise preference/accessibility are important when considering the type of exercise for an individual. LBPP treadmills decrease pain in individuals with knee OA during walking. Pain scores during unweighted walking show moderate to good reliability for individuals with knee OA. This study provides an unweighting protocol to use clinically to determine the Body Weight Support needed to decrease pain.

Analysis of running gait kinematics using an OptoGait at varying degrees of loading on a lower body positive pressure treadmill

Purpose: The use of lower body positive pressure (LBPP) treadmills is becoming more apparent in both rehabilitation and as a supplementary training tool. LBPP treadmills have been shown to reduce ground reaction forces associated with running, whilst maintaining a cardiovascular training stimulus. Additionally, LBPP treadmills are being utilised in orthopaedic, elderly and neurological rehabilitation protocols, due to the ability to offload the forces experienced by lower limbs. The current study aims to investigate the spatiotemporal parameters of the gait cycle at various degrees of body weight support.

Effect of lower body positive pressure aerobic training on fall risk in patients with diabetic polyneuropathy: randomized controlled trial.

Retarded task-oriented gait, balance performance and increased fall risk are among the most debilitating problems in patients with diabetic polyneuropathy (DPN). The lower body positive pressure (LBPP) training was recently introduced in the field of rehabilitation, but evaluating the effects of the LBPP on gait, balance and fall risk in patients with DPN has not been thoroughly investigated. The aim of this study was to evaluate the effect of LBPP treadmill training program on task-oriented gait, balance performance and fall risk in patients with DPN. Single-blinded, randomized-controlled trial. Rehabilitative outpatient unit. Sixty-two patients with DPN were randomly assigned into 5-groups; group-A (100% weight-bearing; N.=12), group-B (75% weight-bearing; N.=13), group-C (50% weight-bearing; N.=13), group-D (25% weight-bearing; N.=12) and group-E (control group; N.=12). The intervention groups (A, B, C, D) received moderate intensity aerobic exercise training (AET) program (30-45 minutes, 50-70% heart rate reserve) on the AlterG (AlterG, Inc., Fremont, CA, USA) treadmill for 12-weeks. Task-oriented gait, balance performance and the fall risk were evaluated at baseline (evaluation-1), after 12-weeks (evaluation-2) and 12-weeks poststudy cessation (evaluation-3; follow-up) for all groups using the Tinetti balance assessment tool. At evaluation-2, there were significant "within-groups" increases in the balance, gait and fall risk scores. There were significant "between-groups" differences in the same evaluated variables, with the highest increases were in group-B (P<0.05). At evaluation-3, there was a decline in the mean values of the evaluated variables, but still significant increases in the mean values of balance, gait and fall risk compared to the baseline mean values. There were significant "between-groups" differences in all variables, with the highest increases were in group-B (P<0.05). Moderate intensity LBPP treadmill training program can effectively improve task-oriented gait, balance performance, and fall risk scores in patients with DPN. The 25% off-loading weight percentage during the LBPP treadmill training program yielded the most favorable short and long-term improvements compared to the other weight off-loading percentages in patients with DPN. The LBPP aerobic training program is an effective rehabilitation procedure in patients with DPN especially when utilizing the 25% off-loading weight percentage during the LBPP treadmill training program.

Influence Of Running Direction On Metabolic Costs May Be Attenuated By Body Weight Support

During running on land, backward running produces greater metabolic and muscular demands than when running forward at the same speed. This type of research is important to identify the similarities and differences of forward and backward running, in order to best prescribe backward running as a cross-training stimulus for forward running. PURPOSE: The purpose of this study was to investigate the influence of running direction on metabolic, biomechanical, and perceptual demands during running at different levels of body weight support (BWS). METHODS: Thirteen participants ran forward and backward on a lower body positive pressure treadmill at 0%BWS, 20%BWS, and 50%BWS conditions at the same speed. We measured oxygen uptake (VO2), heart rate (HR), muscle activity (rectus femoris, biceps femoris, tibialis anterior, gastrocnemius), and stride frequency during the tests. Additionally, we calculated metabolic cost of transport (CoT). Furthermore, we used rating of perceived exertion (RPE) and feeling scale to investigate participants’ perceptual demands during the tests. VO2, HR, CoT, RPE, feeling scale, muscle activity, and stride frequency were analyzed using a 2 (directions) x 3 (BWS) repeated measures analysis of variance (α = 0.05). RESULTS: VO2, HR, and CoT were influenced by the interaction of BWS and running direction (P < 0.01). For example, CoT during backward running were greater than when running forward only when running at 0%BWS (4.5 ± 1.1 and 5.8 ± 1.4 J/kg/m in CoT for forward and backward running, respectively: P < 0.001). However, muscle activity from the rectus femoris, stride frequency, and RPE during backward running were averages of 113.5%, 11.3%, and 2.8 rankings greater than when running forward, respectively, regardless of BWS (P < 0.001). CONCLUSIONS: Backward running may require greater biomechanical and perceptual demands compared to forward running at the same speed, regardless of BWS. However, the influence of a change in running direction on metabolic demands may be attenuated by BWS. Supported by JSPS Grant Number 16 K01663.

The Effect of a Lower Body Positive Pressure Supported Treadmill Exercise Regime on Systemic Biomarkers of Inflammation and Cartilage Degradation in Individuals with Knee Osteoarthritis: A Pilot Study

Background: Knee osteoarthritis (OA) has been linked to a chronic low-grade inflammatory response and altered metabolic activity of articular cartilage. Objective: The purpose of this investigation was to evaluate the effectiveness of a 12-week (3 times/week) lower body positive pressure (LBPP) treadmill walking regime on knee pain and systemic biomarkers of inflammation and cartilage degradation. Methods: Sixteen overweight (BMI &gt; 25 kg/m2) knee OA patients were randomized to a LBPP treadmill walking exercise group (N = 7) or non-exercise control group (N = 9). Baseline and 12-week follow-up assessments evaluated the following dependent variables: acute knee pain during full weight bearing treadmill walking; inflammatory biomarkers (C-reactive protein, interleukin-1β, interleukin-6, s100A8/A9, and tumor necrosis factor-α), and catabolic metabolism of articular cartilage (sCOMP). Results: Knee pain at baseline and follow-up remained unchanged for the non-exercise control group (P &gt; 0.05). However, knee pain for the LBPP exercise group was significantly decreased at follow-up (P ≤ 0.05). No differences in the biomarkers of inflammation and cartilage degradation were observed for between and within group comparisons (all P &gt; 0.05). Conclusions: Data suggested that the LBPP supported walking regime could be effectively used to promote regular weight bearing exercise without exacerbation of knee joint pain and did not increase levels of systemic inflammation or catabolic activity of articular cartilage in overweight knee OA patients. This pilot investigation offers important insight regarding the potential role that the LBPP technology could play in facilitating investigations examining the disease modifying effect of exercise on knee OA pathogenesis.

Temporary application of lower body positive pressure improves intracranial velocities in symptomatic acute carotid occlusion or tight stenosis: A pilot study

Patients with isolated cervical carotid artery occlusion not eligible to recanalization therapies but with compromised intracranial hemodynamics may be at risk of further clinical events. Apart from lying flat until spontaneous recanalization or adjustment of the collateral circulation hopefully occurs, no specific treatment is currently implemented. Improving collateral flow is an attractive option in this setting. Lower body positive pressure (LBPP) is known to result in rapid venous blood shift from the lower to the upper body part, in turn improving cardiac preload and output, and is routinely used in acute hemorrhagic shock. We report here cerebral blood flow velocities measured during LBPP in this patient population. This is a retrospective analysis of the clinical, physiological, and transcranial Doppler monitoring data collected during and 15 min after LBPP in 21 consecutive patients (10 females, median age: 54 years) with recently symptomatic isolated carotid occlusion/tight stenosis (unilateral in 18) mostly due to atherosclerosis or dissection. LBPP was applied for 90 min at a median 5 days after symptom onset. At baseline, middle-cerebral artery velocities were markedly lower on the symptomatic, as compared to asymptomatic, side. LBPP significantly improved blood flow velocities in both the symptomatic and asymptomatic middle-cerebral artery as well as the basilar artery, which persisted 15 min after discontinuing the procedure. LBPP also resulted in mild but significant increases in mean arterial blood pressure. LBPP improved intracranial hemodynamics downstream recently symptomatic carotid occlusion/tight stenosis as well as in the contralateral and posterior circulations, which persisted after LBPP deflation. Randomized trials should determine if this easy-to-use, noninvasive, nonpharmacologic approach has long-lasting benefits on the intracranial circulation and improves functional outcome.

Preliminary Evidence of Orthostatic Intolerance and Altered Cerebral Vascular Control Following Sport-Related Concussion.

Concussions have been shown to result in autonomic dysfunction and altered cerebral vascular function. We tested the hypothesis that concussed athletes (CA) would have altered cerebral vascular function during acute decreases and increases in blood pressure compared to healthy controls (HC). Ten CA (age: 20 ± 2 y, 7 females) and 10 HC (age: 21 ± 2 y, 6 females) completed 5 min of lower body negative pressure (LBNP; −40 mmHg) and 5 min of lower body positive pressure (LBPP; 20 mmHg). Protocols were randomized and separated by 10 min. Mean arterial pressure (MAP) and middle cerebral artery blood velocity (MCAv) were continuously recorded. Cerebral vascular resistance (CVR) was calculated as MAP/MCAv. Values are reported as change from baseline to the last minute achieved (LBNP) or 5 min (LBPP). There were no differences in baseline values between groups. During LBNP, there were no differences in the change for MAP (CA: −23 ± 18 vs. HC: −21 ± 17 cm/s; P = 0.80) or MCAv (CA: −13 ± 8 vs. HC: −18 ± 9 cm/s; P = 0.19). The change in CVR was different between groups (CA: −0.08 ± 0.26 vs. HC: 0.18 ± 0.24 mmHg/cm/s; P = 0.04). Total LBNP time was lower for CA (204 ± 92 s) vs. HC (297 ± 64 s; P = 0.04). During LBPP, the change in MAP was not different between groups (CA: 13 ± 6 vs. HC: 10 ± 7 mmHg; P = 0.32). The change in MCAv (CA: 7 ± 6 vs. HC: −4 ± 13 cm/s; P = 0.04) and CVR (CA: −0.06 ± 0.27 vs. HC: 0.38 ± 0.41 mmHg/cm/s; P = 0.03) were different between groups. CA exhibited impaired tolerance to LBNP and had a different cerebral vascular response to LBPP compared to HC.

Analysis of 3-D Kinematics Using H-Gait System during Walking on a Lower Body Positive Pressure Treadmill.

Recently, treadmills equipped with a lower-body positive-pressure (LBPP) device have been developed to provide precise body weight support (BWS) during walking. Since lower limbs are covered in a waist-high chamber of an LBPP treadmill, a conventional motion analysis using an optical method is impossible to evaluate gait kinematics on LBPP. We have developed a wearable-sensor-based three-dimensional motion analysis system, H-Gait. The purpose of the present study was to investigate the effects of BWS by a LBPP treadmill on gait kinematics using an H-Gait system. Twenty-five healthy subjects walked at 2.5 km/h on a LBPP treadmill under the following three conditions: (1) 0%BWS, (2) 25%BWS and (3) 50%BWS conditions. Acceleration and angular velocity from seven wearable sensors were used to analyze lower limb kinematics during walking. BWS significantly decreased peak angles of hip adduction, knee adduction and ankle dorsiflexion. In particular, the peak knee adduction angle at the 50%BWS significantly decreased compared to at the 25%BWS (p = 0.012) or 0%BWS (p < 0.001). The present study showed that H-Gait system can detect the changes in gait kinematics in response to BWS by a LBPP treadmill and provided a useful clinical application of the H-Gait system to walking exercises.

Effect of Uphill Running on VO2, Heart Rate and Lactate Accumulation on Lower Body Positive Pressure Treadmills.

Lower body positive pressure treadmills (LBPPTs) as a strategy to reduce musculoskeletal load are becoming more common as part of sports conditioning, although the requisite physiological parameters are unclear. To elucidate their role, ten well-trained runners (30.2 ± 3.4 years; VO2max: 60.3 ± 4.2 mL kg−1 min−1) ran at 70% of their individual velocity at VO2max (vVO2max) on a LBPPT at 80% body weight support (80% BWSet) and 90% body weight support (90% BWSet), at 0%, 2% and 7% incline. Oxygen consumption (VO2), heart rate (HR) and blood lactate accumulation (LA) were monitored. It was found that an increase in incline led to increased VO2 values of 6.8 ± 0.8 mL kg−1 min−1 (0% vs. 7%, p < 0.001) and 5.4 ± 0.8 mL kg−1 min−1 (2% vs. 7%, p < 0.001). Between 80% BWSet and 90% BWSet, there were VO2 differences of 3.3 ± 0.2 mL kg−1 min−1 (p < 0.001). HR increased with incline by 12 ± 2 bpm (0% vs. 7%, p < 0.05) and 10 ± 2 bpm (2% vs. 7%, p < 0.05). From 80% BWSet to 90% BWSet, HR increases of 6 ± 1 bpm (p < 0.001) were observed. Additionally, LA values showed differences of 0.10 ± 0.02 mmol l−1 between 80% BWSet and 90% BWSet. Those results suggest that on a LBPPT, a 2% incline (at 70% vVO2max) is not yet sufficient to produce significant physiological changes in VO2, HR and LA—as opposed to running on conventional treadmills, where significant changes are measured. However, a 7% incline increases VO2 and HR significantly. Bringing together physiological and biomechanical factors from previous studies into this practical context, it appears that a 7% incline (at 80% BWSet) may be used to keep VO2 and HR load unchanged as compared to unsupported running, while biomechanical stress is substantially reduced.

Gastrocnemius Medialis Contractile Behavior Is Preserved During 30% Body Weight Supported Gait Training.

Rehabilitative body weight supported gait training aims at restoring walking function as a key element in activities of daily living. Studies demonstrated reductions in muscle and joint forces, while kinematic gait patterns appear to be preserved with up to 30% weight support. However, the influence of body weight support on muscle architecture, with respect to fascicle and series elastic element behavior is unknown, despite this having potential clinical implications for gait retraining. Eight males (31.9 ± 4.7 years) walked at 75% of the speed at which they typically transition to running, with 0% and 30% body weight support on a lower-body positive pressure treadmill. Gastrocnemius medialis fascicle lengths and pennation angles were measured via ultrasonography. Additionally, joint kinematics were analyzed to determine gastrocnemius medialis muscle–tendon unit lengths, consisting of the muscle's contractile and series elastic elements. Series elastic element length was assessed using a muscle–tendon unit model. Depending on whether data were normally distributed, a paired t-test or Wilcoxon signed rank test was performed to determine if body weight supported walking had any effects on joint kinematics and fascicle–series elastic element behavior. Walking with 30% body weight support had no statistically significant effect on joint kinematics and peak series elastic element length. Furthermore, at the time when peak series elastic element length was achieved, and on average across the entire stance phase, muscle–tendon unit length, fascicle length, pennation angle, and fascicle velocity were unchanged with respect to body weight support. In accordance with unchanged gait kinematics, preservation of fascicle–series elastic element behavior was observed during walking with 30% body weight support, which suggests transferability of gait patterns to subsequent unsupported walking.

Effects of unweighting on gait kinematics during walking on a lower-body positive-pressure treadmill in patients with hip osteoarthritis

BackgroundHip osteoarthritis (OA) is a musculoskeletal condition that makes walking difficult due to pain induced by weight-bearing activities. Treadmills that support the body weight (BW) reduce the load on the lower limbs, and those equipped with a lower-body positive-pressure (LBPP) device, developed as a new method for unweighting, significantly reduce pain in patients with knee OA. However, the effects of unweighting on gait kinematics remain unclear in patients with hip OA. Therefore, we investigated the effects of unweighting on kinematics in patients with hip OA during walking on a treadmill equipped with an LBPP device.MethodsA total of 15 women with hip OA and 15 age-matched female controls wore a three-dimensional (3-D) motion analysis system and walked at a self-selected speed on the LBPP treadmill. Data regarding self-reported hip pain using a numeric rating scale (NRS) in which the scores 0 and 10 represented no pain and the worst pain, respectively, under three different BW conditions (100, 75, and 50%) were collected. Moreover, 3-D peak joint angles during gait under each condition were calculated and compared.ResultsIn the hip OA group, the NRS pain scores at 50 and 75% BW conditions significantly decreased compared with that at 100% BW condition (50%, P = 0.002; 75%, P = 0.026), and the peak hip extension angle decreased compared with that in the healthy controls (P = 0.044). In both groups, unweighting significantly decreased the peak hip (P < 0.001) and knee (P < 0.001) flexion angles and increased the peak ankle plantar flexion angle (P < 0.001) during walking.ConclusionsUnweighting by the LBPP treadmill decreased pain in the hip OA group but did not drastically alter the gait kinematics compared with that in the control group. Therefore, regarding the use of the LBPP treadmill for patients with hip OA, clinicians should consider the benefits of pain reduction rather than the kinematic changes.

The influence of increased venous return on right ventricular dyssynchrony during acute and sustained hypoxaemia.

What is the central question of this study? Right ventricular dyssynchrony is a marker of function that is elevated in healthy individuals exposed to acute hypoxia, but does it remain elevated during sustained exposure to high altitude hypoxia, and can it be normalised by augmenting venous return? What is the main finding and its importance? For the first time it is demonstrated that (i) increasing venous return in acute hypoxia restores the synchrony of right ventricular contraction and (ii) dyssynchrony is evident after acclimatisation to high altitude, and remains sensitive to changes in venous return. Therefore, the interpretation of right ventricular dyssynchrony requires consideration the prevailing haemodynamic state. Regional heterogeneity in timing of right ventricular (RV) contraction (RV dyssynchrony; RVD) occurs when pulmonary artery systolic pressure (PASP) is increased during acute hypoxia. Interestingly, RVD is not observed during exercise, a stimulus that increases both PASP and venous return. Therefore, we hypothesised that RVD in healthy humans is sensitive to changes in venous return, and examined whether (i) increasing venous return in acute hypoxia lowers RVD and (ii) if RVD is further exaggerated in sustained hypoxia, given increased PASP is accompanied by decreased ventricular filling at high altitude. RVD, PASP and right ventricular end-diastolic area (RVEDA) were assessed using transthoracic two-dimensional and speckle-tracking echocardiography during acute normobaric hypoxia ( =0.12) and sustained exposure (5-10days) to hypobaric hypoxia (3800m). Venous return was augmented with lower body positive pressure at sea level (LBPP; +10mmHg) and saline infusion at high altitude. PASP was increased in acute hypoxia (20±6 vs. 28±7, P<0.001) concomitant to an increase in RVD (18±7 vs. 38±10, P<0.001); however, the addition of LBPP during hypoxia decreased RVD (38±0 vs. 26±10, P<0.001). Sustained hypoxia increased PASP (20±4 vs. 26±5, P=0.008) and decreased RVEDA (24±4 vs. 21±2, P=0.042), with RVD augmented (14±5 vs. 31±12, P=0.001). Saline infusion increased RVEDA (21±2 vs. 23±3, P=0.008) and reduced RVD (31±12 vs. 20±9, P=0.001). In summary, an increase in PASP secondary to acute and sustained exposure to hypoxia augments RVD, which can be at least partly reduced via increased venous return.

Training on a Lower Body Positive Pressure Treadmill With Body Weight Support does not Improve Aerobic Capacity

Training on a Lower Body Positive Pressure Treadmill With Body Weight Support does not Improve Aerobic Capacity

Lower body positive pressure affects systemic but not cerebral haemodynamics during incremental hyperthermia.

Hyperthermia produces profound redistribution of blood and circulatory reflex function. We investigated the potential for lower body positive pressure (LBPP) to maintain or restore haemodynamics during graded hyperthermia. Eight healthy adults rested supine in a custom-made LBPP box, sealed distal to the iliac crest. Following 5min of normothermic rest, 20mmHg of LBPP was applied and repeated when core temperature (Tcore ) had increased passively by +0.5 and +1°C. Primary dependent variables included mean middle cerebral artery blood velocity (MCAvmean , transcranial Doppler), mean arterial blood pressure (MAP, finger photoplethysmography), heart rate (HR) and partial pressure of end-tidal carbon dioxide (PET CO2 ). The absolute increase in MAP during LBPP was lower at Tcore +1°C (2±3mmHg), compared with normothermia (7±3 p=.01). The modest increase in MCAvmean was unchanged by Tcore (normothermia, 2±3cm/s; +0.5°C, 3±3cm/s and +1°C, 3±4cm/s, p=.74). By design, PET CO2 was unchanged in all conditions from normothermic baseline (42±1, p=.81). LBPP-induced changes in HR were greater at +0.5°C (-13±4b/min) and +1°C (-12±6b/min) compared with normothermia (-3±3b/min, p=.01 and p=.01, respectively). These data indicate that despite a significant attenuation in MAP to LBPP with moderate hyperthermia, MCAvmean dynamics were unchanged among the thermal manipulations.

Effect of Body Weight-Supported Exercise on Symptoms of Knee Osteoarthritis: A Follow-up Investigation.

To examine the long-term effect of participation in a 12-week lower-body positive pressure (LBPP)-supported low-load treadmill exercise regime on knee joint pain, physical function, and thigh muscle strength in patients with knee osteoarthritis (OA). Prospective, observational, repeated measures. Clinical orthopedic setting. Nineteen overweight patients with knee OA. Participants exercised under low-load treadmill walking conditions 2×/week for 12 weeks using an amount of LBPP support that minimized knee pain while walking for a period of 30 minutes at a set speed of 3.1 mph at 0-degree incline. Knee pain, function, thigh muscle strength, and body anthropometry were reassessed a minimum of 6 months after completion of the initial exercise regime and compared with results from baseline and postexercise evaluation. Data suggested that: (1) patients were able to maintain improvements in knee joint pain and symptoms; (2) patients continued to report enhanced joint function and improved quality of life; and (3) patients maintained thigh muscle strength gains. Finally, a majority of patients continued to experience significant reductions in acute knee pain during full weight-bearing treadmill walking. Data suggest that improvements in knee pain, joint function, and thigh muscle strength associated with participation in a 12-week LBPP-supported low-load exercise regime were maintained well after cessation of the program. These findings have important implications for the development and refinement of exercise strategies and interventions used in the long-term management of joint symptoms associated with knee OA in overweight patients.

Influence Of Running Speed On Muscle Activity During Backward Running With Body Weight Support

A change in running speed influences gait mechanics of running. PURPOSE: The purpose of this study was to investigate the influence of a change in running speed on muscle activity during forward and backward running at different body weight support (BWS) conditions. METHODS: Eleven participants (29.7 ± 12.3 years) ran forward and backward on a lower body positive pressure treadmill at 0%BWS, 20%BWS, and 50%BWS conditions. The running speed conditions consisted of forward and backward running at preferred speed (PS), PS+10%, and PS-10%. Muscle activity from the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius and stride frequency were measured. Muscle activity and stride frequency were analyzed using a 2 (running direction) x 3 (BWS) x 3 (running speed) repeated measures analysis of variance (α = 0.05). RESULTS: Muscle activity from the rectus femoris (P<0.01) and gastrocnemius (P<0.01) were significantly different between running speeds. For example, muscle activity from the rectus femoris (P<0.05) and gastrocnemius (P<0.05) during running at PS were significantly greater than when running at PS-10%, regardless of running direction and BWS. Furthermore, muscle activity from the rectus femoris (P<0.01) and gastrocnemius (P<0.05) during running at PS+10% were significantly greater than when running at PS, regardless of running direction and BWS. Stride frequency was influenced by the interaction of running direction and running speed (P<0.05). Using the pairwise comparisons, stride frequency during running at PS was significantly higher than that of running at PS-10% only when running forward and backward at 0%BWS (e.g., 84.5 strides/min and 82.0 strides/min for backward running at PS and PS-10% conditions, respectively: P<0.05). Furthermore, stride frequency during running at PS+10% was significantly higher than that of running at PS during forward and backward running at 0%BWS (P<0.05). CONCLUSIONS: Muscle activity from the rectus femoris and gastrocnemius during running may increase with increasing running speed, regardless of BWS and running direction. However, unique biomechanical strategies for the increased muscle activity from the lower extremity may exist for running with BWS.

Validation Of Step Length Between An Anti-Gravity Treadmill And A 2-Dimensional Camera System

Lower body positive pressure treadmills (LBPPT) allow patients to walk in a gravity reduced environment of their total body weight with new embedded gait analysis module capable of documenting gait outcomes. PURPOSE: To validate step length (SL) measurement calculated by the LBPPT against a two-dimensional camera system. METHODS: Nine participants (5 male and 4 females; mean age 30.8 years) walked and ran for five minutes at 3mph, 4mph, 5mph, and 6mph on a lower body positive pressure treadmill (LBPPT). At each speed the subjects were unweighted at 80%, 60%, 40% and 20% of their total body weight (BW). A side camera view was employed to record step length. Five SL measurements from the middle minute were taken from each video from heel to heel and averaged to represent SL for each BW and speed. The right and left SL measurements from the treadmill were averaged as a composite SL measurement for analysis. Intraclass correlation coefficients were estimated for the average of five trials of the video data. Pearson correlations were calculated between step length from the treadmill and video. Correlations were considered significant at alpha .05. RESULTS: All speeds and body weight conditions exhibited excellent reliability (ICC > 0.90) for the average of five trials for the video analysis. The correlations between the treadmill and video analysis for the speeds of 3 and 4 mph showed varied correlations fluctuating from poor to good (r=.21-.98) with correlations greater than r=.85 showing statistical significance. The correlations between treadmill and cameras for the 5 and 6 mph speeds showed no statistically significant correlations ranging from r=.02-.69. CONCLUSIONS: The gait analysis module of the LBPPT does not measure direct step length from the instrumented belt after the transition from walking to running. The LBPPT might be using an algorithm to extrapolate the anticipated step length if the subject were not on the treadmill.

Psychological Responses To Acute Exercise: A Comparison Of Lower Body Positive Pressure Treadmill And Cycling

Acute aerobic exercise has been shown to improve mood and affect in active adults. Lower body positive pressure treadmills (LBPPT) have been utilized to reduce loading on the musculoskeletal system and to provide an alternative to running and cross-training. While the biomechanical and physiological responses to the LBPPTs have been well-researched, little is known about psychological responses and how this compares to other forms of exercise. PURPOSE: To investigate mood, affect, and self-efficacy, following an acute, hard-intensity exercise session and compare these responses between three modalities: cycling, LBPPT running and treadmill running (NT). METHODS: 10 active adults (average age = 30 years, SD = 10.4 years) completed a 30min, high-intensity exercise session on each of three modalities in a randomized order: bike, LBPPT, and NT. Intensity was determined as 85% age-predicted maximum heart rate. Before and after each session, feeling, arousal, affect and self-efficacy were determined using the Feeling and Arousal scale (FAS), Activation-Deactivation Adjective Checklist (ADACL), and Generalized Self-efficacy survey (GSE). RESULTS: From baseline to post-exercise, there was a significant increase in feeling (2.4 ± 0.31 vs. 3.33 ± 0.29, p=0.021), arousal (3.23 ± 0.23 vs. 4.07 ± 0.31, p=0.006), and self-efficacy (31.83± 0.83 vs. 33.97± 1.16, p= 0.013) across all three modalities. However, when compared among the three modalities, there was no observed significant change in self-efficacy values from baseline to post-exercise (p=0.708). For affect (ADACL), there was an observed significant increase in energetic arousal (25.9 ± 1.12 vs. 29.43 ± 1.36, p= 0.023) and a decrease in state anxiety (20.93± 1.73 vs. 17.367± 1.08, p= 0.041) from baseline to post-exercise across all modalities, however, this did not significantly differ among the modalities. There were no other significant changes in affect observed. CONCLUSION: Self-efficacy, feeling, energetic arousal, and anxiety improves following acute, hard intensity exercise sessions; however, these changes do not differ based on exercise modality. Psychological responses to acute exercise differs between runners and non-runners. Future research should investigate how these responses may differ between the two groups based on modality.

Stable Body Temperature in Trained Runners Despite Localized Heating within Alter GTM Treadmill

Lower body positive pressure treadmills (LBPPT) are beneficial for rehabilitation and exercise training. Running on a LBPP treadmill (AlterGTM) involves sealing the lower half of the body in a high air pressure flexible sealed chamber to simulate exercise at lower body weight. The effects of the sealed chamber on treadmill and tympanic temperature during exercise have yet to be investigated. The purpose of the study was to measure treadmill and tympanic temperatures while participants were running on a normal treadmill and compare temperatures to running on a LBPP treadmill. Fifteen well-trained runners completed three running trials on a LBPP treadmill at 60, 75, and 85% of body weight (BW). A 100% BW trial was run on a normal treadmill. Participants ran at three steady state speeds (2.9, 3.4, and 3.8 m·s-1) for four minutes each. Room air, tympanic, and LBPPT chamber temperatures (°C) were recorded. The main finding was that treadmill temperature was significantly greater among the three BW conditions on the LBPPT compared to normal treadmill (average of all LBPPT, 30.7 ± 2.3°C, normal treadmill, 22.5 ± 2.1°C). Tympanic temperatures were not different between all BW conditions. Runners may use LBPPT for rehabilitation or low-impact training yet should be aware of the increase in LBPP chamber temperature.