Lower Body Positive Pressure Treadmill Research Articles

Muscle Activation and Estimated Relative Joint Force During Running with Weight Support on a Lower-Body Positive-Pressure Treadmill.

Running on a lower-body positive-pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100%, 80%, 60%, 40%, and 20% body weight (BW). Surface electromyography, ground reaction force, and running characteristics were measured. Relative knee and ankle joint forces were estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and antigravity forces. At 20% BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100% BW values. Plantar flexors decreased to 52% and 58% at 20% BW, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle). It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect of unweighting on estimated knee force was more pronounced than on ankle force.

Overspeed HIIT in Lower-Body Positive Pressure Treadmill Improves Running Performance.

Optimal high-intensity interval training (HIIT) regimens for running performance are unknown, although most protocols result in some benefit to key performance factors (running economy (RE), anaerobic threshold (AT), or maximal oxygen uptake (VO2max)). Lower-body positive pressure (LBPP) treadmills offer the unique possibility to partially unload runners and reach supramaximal speeds. We studied the use of LBPP to test an overspeed HIIT protocol in trained runners. Eleven trained runners (35 ± 8 yr, VO2max, 55.7 ± 6.4 mL·kg⁻¹·min⁻¹) were randomized to an LBPP (n = 6) or a regular treadmill (CON, n = 5), eight sessions over 4 wk of HIIT program. Four to five intervals were run at 100% of velocity at VO2max (vVO2max) during 60% of time to exhaustion at vVO2max (Tlim) with a 1:1 work:recovery ratio. Performance outcomes were 2-mile track time trial, VO2max, vVO2max, vAT, Tlim, and RE. LBPP sessions were carried out at 90% body weight. Group-time effects were present for vVO2max (CON, 17.5 vs. 18.3, P = 0.03; LBPP, 19.7 vs. 22.3 km·h⁻¹; P < 0.001) and Tlim (CON, 307.0 vs. 404.4 s, P = 0.28; LBPP, 444.5 vs. 855.5, P < 0.001). Simple main effects for time were present for field performance (CON, -18; LBPP, -25 s; P = 0.002), VO2max (CON, 57.6 vs. 59.6; LBPP, 54.1 vs. 55.1 mL·kg⁻¹·min⁻¹; P = 0.04) and submaximal HR (157.7 vs. 154.3 and 151.4 vs. 148.5 bpm; P = 0.002). RE was unchanged. A 4-wk HIIT protocol at 100% vVO2max improves field performance, vVO2max, VO2max and submaximal HR in trained runners. Improvements are similar if intervals are run on a regular treadmill or at higher speeds on a LPBB treadmill with 10% body weight reduction. LBPP could provide an alternative for taxing HIIT sessions.

Effects of Lower Body Positive Pressure on Blood Pressure and Heart Rate in College Age Students

Elucidating the Effects of 40 Minutes of Lower Body Positive Pressure on Blood Pressure and Heart Rate in College Age Students Lower Body Positive Pressure (LBPP) has become a popular exercise modality treatment in the physical therapy rehabilitation setting for lower extremities in post-injury/operative patients. PURPOSE: The purpose of this study was to investigate the effects of 40 minutes LBPP at a percent unloading of 75%, 50%, and 25% body weight on resting SBP/DBP and HR in a standing position in the Alter-G. METHODS: Subjects included 10 college-age students (3 males and 7 females) who were screened for this investigation and signed an approved Informed Consent Form through the University Institutional Review Board. All subjects were asked to sit for 5 minutes prior to testing. Any subject with a resting SBP/DBP greater than 139 mmHg/88 mmHg was excluded from participation in the study. Resting HR, SBP and DBP measurements were recorded every ten minutes at each percent body weight by using an electronic Omron Blood Pressure Monitor (Module HEM-790IT). Barometric pressure inside the Alter-G cockpit was recorded by a Thomas Scientific Hygrometer Thermometer Barometer DP. RESULTS: A repeated measures multivariate analysis of variance (MANOVA) was performed across conditions to analyze data at the p<.05 significance level. Mean barometric pressure within the Alter-G increased significantly from 755.85 mmHg at 100% body weight (BW) to 766.8 mmHg, 778.88 mmHg, and 790.92 mmHg at 75% BW, 50% BW, and 25% BW, respectively, (p<.001). Mean systolic blood pressure varied from 112.8 mmHg at 100% BW to 111.6 mmHg, 114.7 mmHg, and 114.3 mmHg at 75% BW, 50% BW, and 25% BW, respectively. Mean diastolic blood pressure varied from 76.3 mmHg at 100% BW to 74.8 mmHg, 75.8 mmHg, 75.7 mmHg at 75% BW, 50% BW, and 25% BW, respectively. Systolic and diastolic blood pressures were found not to be significant across conditions (p=.619), (p=.642). Mean heart rate varied from 81.6 bpm at 100% BW to 76.3 bpm, 74.1 bpm and 72.3 bpm at 75% BW, 50% BW, and 25% BW, respectively. Heart rate was found not to be significant through MANOVA analyses, (p<.161). CONCLUSION: The clinical relevance of such findings indicates that the LBPP Treadmills will not adversely affect systolic and diastolic parameters in a college-age population with 40 minutes of LBPP. Future studies should now include an older population with similar time exposure to LBPP to see if similar findings are found.

Influence Of Unweighting On Muscle Oxygenation And Vo2 During Running On A Lower-body Positive-pressure Treadmill

The influence of unweighting using a lower body positive pressure treadmill (PPT) on oxygen consumption (VO2) has been previously explored. However, it is unknown how different body weight settings (BWSet) in a PPT influence muscle oxygen saturation. PURPOSE:To describe the relationship between tissue oxygenation and VO2 while running across multiple BWSet on a PPT. METHODS: Six experienced runners participated in this study. Tissue saturation index (TSI), oxygenated hemoglobin (O2Hb), and deoxygenated hemoglobin (HHb) levels were obtained using a near infrared spectroscopy (NIRS) unit secured on the right vastus lateralis. VO2 data were collected using a metabolic cart. Subjects ran at a self-reported “easy” training pace for 4 minutes at 40, 60, 80, and 100% BWSet (randomized order), followed by 4 minutes of rest. Preceding each stage, subjects walked at 3 mph for 1 minute at 100% BWSet. The NIRS data from the last 30 seconds of each running stage were averaged and data from the last 30 seconds of each walking stage were subtracted to serve as a reference measurement. Linear mixed effects models were used to determine whether BWSet influenced VO2 and NIRS parameters. For the first model, BWSet was analyzed as a categorical variable and pairwise comparisons were then used to determine differences between each BWSet. For the second model, all data were normalized to 100% BWSet and analyzed as a continuous variable to allow development of regression models for each parameter. Slopes of the regression equations were then compared using Z-score estimates. RESULTS: When the data were modeled using BWSet categorically, BWSet significantly influenced VO2, TSI, O2Hb, and HHb (p<0.005 for each), and pairwise comparisons revealed significant (p<0.05) differences between each BWSet. When normalized data were modeled using BWSet as a continuous variable, there was a significant linear relationship for each parameter (p<0.005), but the slope for all NIRS parameters (β range: 0.010-0.12) were significantly greater than that for VO2 (β = 0.006). CONCLUSIONS: The results show that VO2 and tissue oxygenation change at different rates for varying BWSet on a PPT. Further research is necessary to determine if altered tissue oxygenation achieved on PPT influences training response.

Influence of Body Weight Support and Direction of Locomotion on Preferred Gait

Previously, no research has investigated differences in preferred gait characteristics during forwards and backwards running at varying body weight (BW) support. PURPOSE: To understand how BW support and direction of locomotion influence descriptors of preferred gait. METHODS: Subjects (n=8; 27.0±11.7 years, 173.8±3.5 cm, 74.0±8.7 kg) performed forward and backward running on a lower body positive pressure treadmill at different levels of BW support (i.e., 0%-80% body weight support). Subjects preferred running speed (PS), preferred stride frequency (PSF), and rate of perceived exertion (RPE) were measured. PS, PSF, and RPE were analyzed using a 2(exercise mode: forward and backward locomotion) x 5(BW support: 0%, 20%, 40%, 60%, and 80%) repeated measures analysis of variance (α= 0.05). RESULTS: PS, PSF, and RPE were not influenced by the interaction of exercise mode and BW support (p > 0.05). PS was different between modes (p < 0.001) and between BW support conditions (p < 0.01). For example, PS increased approximately 3.8%-8.5% and 3.0%-11.9% with decreasing BW support for forward and backward running, respectively. Additionally, PS during forward running was higher than that of backward running at reduced BW support (e.g., 3.4±.9 m/s and 2.5±.5 m/s for forward and backward running at 80% BW support, respectively). Furthermore, PSF (p< 0.001) and RPE (p< 0.01) were different between BW conditions but not different between direction of locomotion (p>0.05). Specifically, PSF (e.g., a decrease of 13.2% during forward running at 0% BW support vs. 80% BW support) and RPE (e.g., a decrease of 19.9% during forward running at 0% BW support vs. 80% BW support) during forward and backward running decreased with decreasing BW support. CONCLUSION: It seems that BW support may have more of an influence on preferred gait characteristics than direction of locomotion since PSF and RPE were not different between directions of locomotion.

Effects of unweighting and speed on in-shoe regional loading during running on a lower body positive pressure treadmill

The purpose of this study was to determine how unweighted running on a lower body positive pressure treadmill (LBPPT) modifies in-shoe regional loading. Ten experienced runners were fit with pressure distribution measurement insoles and ran at 100%, 120%, and 140% of self-reported easy training pace on a LBPPT at 20%, 40%, 60%, 80%, and 100% body weight percentage settings (BWSet). Speeds and BWSet were in random order. A linear mixed effect model (p<0.05 significance level) was used to compare differences in whole foot and regional maximum in-shoe plantar force (FMAX), impulse, and relative load distribution across speeds and BWSet. There were significant main effects (p<0.001) for running speed and BWSet for whole foot Fmax and impulse. The model revealed 1.4% and 0.24% increases in whole foot FMAX (times body weight) and impulse, respectively, for every unit increase in body weight percentage. There was a significant main effect for BWSet on Fmax and relative load (p<0.05) for each of the nine foot regions examined, though four regions were not different between 80% and 100% BWSet. There was a significant (p<0.001) main effect for BWSet on forefoot to rear foot relative load. Linear relationships were found between increases in BWSet and increases in-shoe Fmax and impulse, resulting from regional changes in foot pressure which represent a shift towards forefoot loading, most evident <80% BWSet. Estimating in-shoe regional loading parameters may be useful during rehabilitation and training to appropriately prescribe specific speed and body weight levels, without exceeding certain critical peak force levels while running.

Conversion table for running on lower body positive pressure treadmills.

Lower body positive pressure (LBPP) or antigravity treadmills are becoming increasingly popular in sports and rehabilitation settings. Running at a decreased body weight (BW) reduces metabolic cost, which can be offset by running at faster speeds. To date, however, little is known about how much faster someone must run to offset the reduced metabolic cost. This study aimed to develop a user-friendly conversion table showing the speeds required on an LBPP treadmill to match the equivalent metabolic output on a regular, non-LBPP, treadmill across a range of body weight supports. A total of 20 recreational runners (11 males, 9 females) ran multiple 3-minute intervals on a regular treadmill and then on an LBPP treadmill at 6 different BWs (50-100%, 10% increments). Metabolic outputs were recorded and matched between the regular and LBPP treadmill sessions. Using regression analyses, a conversion table was successfully created for the speeds from 6.4 to 16.1 km·h (4 to 10 mph) in 0.8 km·h (0.5 mph) increments on the regular treadmill and BW proportions of 50, 60, 70, 80, 90, and 100% on an LBPP treadmill. The table showed that a greater increase in speed on the LBPP treadmill was needed with more support (p < 0.001) but that the proportion increase was smaller at higher speeds (p < 0.001). This research has implications for coaches or practitioners using or prescribing training on an LBPP treadmill.

Accuracy of unloading with the anti-gravity treadmill.

Body weight (BW)-supported treadmill training has become increasingly popular in professional sports and rehabilitation. To date, little is known about the accuracy of the lower-body positive pressure treadmill. This study evaluated the accuracy of the BW support reported on the AlterG "Anti-Gravity" Treadmill across the spectrum of unloading, from full BW (100%) to 20% BW. Thirty-one adults (15 men and 16 women) with a mean age of 29.3 years (SD = 10.9), and a mean weight of 66.55 kg (SD = 12.68) were recruited. Participants were weighed outside the machine and then inside at 100-20% BW in 10% increments. Predicted BW, as presented by the AlterG equipment, was compared with measured BW. Significant differences between predicted and measured BW were found at all but 90% through 70% of BW. Differences were small (<5%), except at the extreme ends of the unloading spectrum. At 100% BW, the measured weight was lower than predicted (mean = 93.15%, SD = 1.21, p < 0.001 vs. predicted). At 30 and 20% BW, the measured weight was higher than predicted at 35.75% (SD = 2.89, p < 0.001), and 27.67% (SD = 3.76, p < 0.001), respectively. These findings suggest that there are significant differences between reported and measured BW support on the AlterG Anti-Gravity Treadmill®, with the largest differences (>5%) found at 100% BW and the greatest BW support (30 and 20% BW). These differences may be associated with changes in metabolic demand and maximum speed during walking or running and should be taken into consideration when using these devices for training and research purposes.

A case with below knee amputation due to diabetic foot gangrene using a lower body positive pressure treadmill for prosthetic rehabilitation

A case with below knee amputation due to diabetic foot gangrene using a lower body positive pressure treadmill for prosthetic rehabilitation

Metabolic accommodation to running on a body weight-supported treadmill.

Body weight-supported treadmill training using positive air pressure has become increasingly popular, but little is known about the metabolic adaptations to these treadmills. This study aimed to evaluate the existence and length of a metabolic accommodation period to running on a lower body positive pressure (LBPP) treadmill. A total of eight recreational runners (5 males and 3 females) ran 15 min trials (5 min at 50, 70, and 90 % body weight) on the AlterG Anti-gravity(®) P200 treadmill. No verbal instruction was given on how to run on the device. Their trial pace corresponded to 70-80 % of their velocity measured at [Formula: see text]O2max on a standard treadmill. Trials were continued until no significant metabolic change was observed. Two-way repeated measures analysis of variance was used to analyze changes in [Formula: see text]O2 across trials and levels of unloading. Participants completed 7 trials. Comparing trial 1 to the average of trials 5, 6, and 7, [Formula: see text]O2 decreased from 29.6 ± 3.8 to 23.6 ± 4.4 ml/kg/min at 50 % body weight (~20 % reduction), from 33.7 ± 4.5 to 29.2 ± 5.1 ml/kg/min at 70 % body weight (~13 % reduction), and from 41.0 ± 7.7 to 36.6 ± 5.6 ml/kg/min at 90 % body weight (~11 % reduction). No significant reduction occurred after trial 4 at any level of support. An accommodation effect of running on a treadmill with LBPP was observed and reached after 60 min of running (4 trials of 15 min). The accommodation effect was the largest at the greatest level of body weight support. These data suggest the importance of an accommodation period for reliable measures of metabolic cost to be made.

Muscle Activity During Running With Different Body-Weight-Support Mechanisms: Aquatic Environment Versus Body-Weight-Support Treadmill

Body-weight (BW) support during running can be accomplished using deep-water running (DWR; 100% BW support) and a lower-body positive-pressure (LBPP) treadmill. To compare lower-extremity muscle activity during DWR and running on an LBPP treadmill at matched stride frequency. Eight subjects (40 ± 6.5 y, 173 ± 7.2 cm, 66.9 ± 11.7 kg) completed 4 running conditions all at a preferred stride frequency that was determined while running with no support. Two conditions were running on the LBPP treadmill at 60% and 80% of BW, and the other 2 conditions were different DWR styles: high knee (DWR-HK) and cross-country (DWR-CC). Average (AVG) and root-mean-square (RMS) electromyography (rectus femoris, biceps femoris, gastrocnemius, and tibialis anterior) were each compared among conditions (repeated-measures analysis of variance). Results for AVG and RMS variables were identical for statistical tests for each muscle. Rectus femoris electromyography during DWR-HK was lower than that of DWR-CC (P < .05) but not different than either 60% BW or 80% BW (P > .05). Biceps femoris electromyography was less during DWR-HK than DWR-CC (P < .05) but greater during DWR-HK than either BW 60% or BW 80% (P < .05). Neither gastrocnemius nor tibialis anterior electromyography differed between conditions (P > .05). Neither the mechanism of BW support nor style of DWR influenced gastrocnemius or tibialis anterior muscle activity during running at the same stride frequency. However, rectus femoris and biceps femoris muscle activity were influenced by not only the mechanism of BW support but also the style of DWR.

A Conversion Table For Running On Lower Body Positive Pressure (LBPP) Treadmills

A Conversion Table For Running On Lower Body Positive Pressure (LBPP) Treadmills

Effect of Weight Support on Tibial Accelerations During a Lower-Body Positive Pressure Treadmill Cadence-Controlled Run

Effect of Weight Support on Tibial Accelerations During a Lower-Body Positive Pressure Treadmill Cadence-Controlled Run

Cardiovascular responses in older adults with total knee arthroplasty at rest and with exercise on a positive pressure treadmill

We investigated cardiovascular responses at rest and during submaximal exercise on a lower body positive pressure treadmill in older adults with total knee arthroplasty (TKA). Twenty-four adults (mean age 64.6 ± 7.9 SD) with unilateral TKA participated (median time since surgery 8.0 weeks). Heart rate and blood pressure responses were measured at rest standing on the positive pressure treadmill with 0, 10, 20, and 30 mmHg applied. Heart rate, blood pressure, oxygen consumption, minute ventilation, knee pain and perceived exertion were measured during submaximal exercise tests (0 and 40% body weight support) conducted 1 week apart. At rest there were no differences in blood pressure across different treadmill pressures, but heart rate was significantly lower when 30 mmHg was applied compared to ambient pressure conditions (P < 0.05). Participants averaged 5.1 exercise test stages with 0% body weight support (maximum speed 2.5 mph, 0% incline) and 6.4 stages with 40% body weight support (maximum speed 3.0 mph, 10% incline). During exercise, heart rate, systolic blood pressure, oxygen consumption, and minute ventilation were lower when 40% body weight support was provided for a given test stage (P < 0.01). Diastolic blood pressure, knee pain and perceived exertion did not differ with body weight support but increased with increasing exercise test stages (P < 0.05). Provision of body weight support allowed TKA patients to walk at faster speeds and/or to tolerate greater incline with relatively lower levels of heart rate, blood pressure, and oxygen consumption.

High intensity interval training at overspeed in a lower body positive pressure treadmill improves performance in trained runners

Introduction: Exercise training of the lower limbs mediates localised conduit and resistance artery adaptations in the active region and systemic adaptations in the upper limbs. These changes to the vasculature are largelymediated through elevations in shear stress. Whether microcirculatory vascular responses to lower limb training occur systemically, and whether shear stress contributes to such adaptations, is currently unknown. Methods: Nine subjects completed an 8-week cycle ergometer training study, with unilateral cuff inflation around the forearm to unilaterally manipulate upper limb blood flow and shear stress during each exercise bout. To test skin microvascular function at 0, 4 and 8 weeks of exercise training, we measured laser-Doppler skin flux in response to localised disk heating at 33, 42 and 44 ◦C. Cutaneous vascular conductance was derived from skin flux and blood pressure values. Results: Acutely, the onset of cycling increased skin flux (12.1±4.1 to 131.7±35.0 PU) and temperature (31.7±0.4 to 33.6±0.9 ◦C), whilst in the cuffed arm (60mmHg) skin flux (11.91±2.22 to 52.92PU) and temperature (31.5±0.3 to 31.7±0.8 ◦C) responses were attenuated or absent (2-way ANOVA interaction-effect; both P<0.001). Chronically, after 8 weeks of cycling, skin flux responses during the plateau phase of heating at 42 ◦C (3.19±0.32 to 2.38±0.41PU/mmHg) and 44 ◦C (3.65±0.30 to 2.84±0.44PU/mmHg) were significantly lower in the uncuffed arm, but unchanged in the cuffed limb at (42 ◦C: 3.10±0.36 to 2.76±0.30PU/mmHg, 44 ◦C: 3.70±0.39 to 3.46±0.30PU/mmHg). Discussion: Cycling exercise is associated with increased skin perfusion in the upper limbs, an effect which is ameliorated by placement of a pressure cuff. Cycle training decreased the skin vasodilator response to an identical local heating stimulus, suggesting enlargement of the capillary bed and associated increase in skin blood flow transit time. We speculate that this impact of leg exercise training in the upper limbs may enhance systemic heat loss following training. No changes in the contra-lateral cuffed arm were apparent, suggesting that repeated increases in shear stress may mediate some of this adaptation in the skin microcirculation as a result exercise training.

Running on a Lower-Body Positive Pressure Treadmill: VO2max, Respiratory Response, and Vertical Ground Reaction Force

Purpose: This study investigated maximal oxygen consumption (VO2max) and time to exhaustion while running on a lower-body positive pressure treadmill (LBPPT) at normal body weight (BW) as well as how BW support affects respiratory responses, ground reaction forces, and stride characteristics. Method: Twelve runners performed VO2max tests on a regular treadmill and an LBPPT. Furthermore, they performed steady-state running (10 km/hr, 14 km/hr, and 18 km/hr) and high-speed running (20 km/hr and 22 km/hr) at four different BWs on the LBPPT. VO2, heart rate, ventilation, and breathing frequency as well as vertical ground reaction force (vGRF) and stride characteristics were measured. Results: VO2max could be obtained on both treadmills, although time to exhaustion was 34.5% longer on the LBPPT. VO2, ventilation, and heart rate decreased linearly with increasing BW support at steady-state running, while breathing rate remained unaffected by increasing BW support. Ground reaction force was markedly reduced with increasing BW support. The contact time decreased and flight time increased with increasing BW support. The step frequency decreased and step length increased to some extent with increasing BW support. Conclusions: VO2max can be achieved on an LBPPT at 100% BW with an incline-running protocol. The LBPPT is a suitable training device for athletes and allows training at high running speeds and high aerobic stimuli with the benefit of low vGRF and a near-normal movement pattern, although manipulation of gravitational weight causes some adaptations in locomotion.

Anti‐gravity treadmills are effective in reducing knee forces

Lower body positive pressure (LBPP) treadmills permit significant unweighting of patients and have the potential to enhance recovery following lower limb surgery. We determined the efficacy of an LBPP treadmill in reducing knee forces in vivo. Subjects, implanted with custom electronic tibial prostheses to measure forces in the knee, were tested on a treadmill housed within a LBPP chamber. Tibiofemoral forces were monitored at treadmill speeds from 1.5 mph (0.67 m/s) to 4.5 mph (2.01 m/s), treadmill incline from -10° to +10°, and four treadmill chamber pressure settings adjusted to decrease net treadmill reaction force from 100% to 25% of the subject's body weight (BW). The peak axial tibiofemoral force ranged from 5.1 times BW at a treadmill speed of 4.5 mph (2.01 m/s) and a pressure setting of 100% BW to 0.8 times BW at 1.5 mph (0.67 m/s) and a pressure setting of 25% BW. Peak knee forces were significantly correlated with walking speed and treadmill reaction force (R(2) = 0.77, p = 0.04). The LBPP treadmill might be an effective tool in the rehabilitation of patients following lower-extremity surgery. The strong correlation between tibiofemoral force and walking speed and treadmill reaction forces allows for more precisely achieving the target knee forces desired during early rehabilitation.

Improved Clinical Status, Quality of Life, and Walking Capacity in Parkinson's Disease After Body Weight-Supported High-Intensity Locomotor Training

ObjectiveTo evaluate the effect of body weight-supported progressive high-intensity locomotor training in Parkinson's disease (PD) on (1) clinical status; (2) quality of life; and (3) gait capacity. DesignOpen-label, fixed sequence crossover study. SettingUniversity motor control laboratory. ParticipantsPatients (N=13) with idiopathic PD (Hoehn and Yahr stage 2 or 3) and stable medication use. InterventionsPatients completed an 8-week (3 × 1h/wk) training program on a lower-body positive-pressure treadmill. Body weight support was used to facilitate increased intensity and motor challenges during treadmill training. The training program contained combinations of (1) running and walking intervals, (2) the use of sudden changes (eg, in body weight support and speed), (3) different types of locomotion (eg, chassé, skipping, and jumps), and (4) sprints at 50 percent body weight. Main Outcome MeasuresThe Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Parkinson's Disease Questionnaire-39 items (PDQ-39), and the six-minute walk test were conducted 8 weeks before and pre- and posttraining. ResultsAt the end of training, statistically significant improvements were found in all outcome measures compared with the control period. Total MDS-UPDRS score changed from (mean ± 1SD) 58±18 to 47±18, MDS-UPDRS motor part score changed from 35±10 to 29±12, PDQ-39 summary index score changed from 22±13 to 13±12, and the six-minute walking distance changed from 576±93 to 637±90m. ConclusionsBody weight-supported progressive high-intensity locomotor training is feasible and well tolerated by patients with PD. The training improved clinical status, quality of life, and gait capacity significantly.

Maximal Physiological Parameters during Partial Body-Weight Support Treadmill Testing

This study investigated maximal cardiometabolic response while running in a lower body positive pressure treadmill (antigravity treadmill (AG)), which reduces body weight (BW) and impact. The AG is used in rehabilitation of injuries but could have potential for high-speed running, if workload is maximally elevated. Fourteen trained (nine male) runners (age 27 ± 5 yr; 10-km personal best, 38.1 ± 1.1 min) completed a treadmill incremental test (CON) to measure aerobic capacity and heart rate (VO(2max) and HR(max)). They completed four identical tests (48 h apart, randomized order) on the AG at BW of 100%, 95%, 90%, and 85% (AG100 to AG85). Stride length and rate were measured at peak velocities (V(peak)). VO(2max) (mL.kg(-1).min(-1)) was similar across all conditions (men: CON = 66.6 (3.0), AG100 = 65.6 (3.8), AG95 = 65.0 (5.4), AG90 = 65.6 (4.5), and AG85 = 65.0 (4.8); women: CON = 63.0 (4.6), AG100 = 61.4 (4.3), AG95 = 60.7 (4.8), AG90 = 61.4 (3.3), and AG85 = 62.8 (3.9)). Similar results were found for HR(max), except for AG85 in men and AG100 and AG90 in women, which were lower than CON. V(peak) (km.h(-1)) in men was 19.7 (0.9) in CON, which was lower than every other condition: AG100 = 21.0 (1.9) (P < 0.05), AG95 = 21.4 (1.8) (P < 0.01), AG90 = 22.3 (2.1) (P < 0.01), and AG85 = 22.6 (1.6) (P < 0.001). In women, V(peak) (km.h(-1)) was similar between CON (17.8 (1.1) ) and AG100 (19.3 (1.0)) but higher at AG95 = 19.5 (0.4) (P < 0.05), AG90 = 19.5 (0.8) (P < 0.05), and AG85 = 21.2 (0.9) (P < 0.01). The AG can be used at maximal exercise intensities at BW of 85% to 95%, reaching faster running speeds than normally feasible. The AG could be used for overspeed running programs at the highest metabolic response levels.

Leg intramuscular pressures and in vivo knee forces during lower body positive and negative pressure treadmill exercise

Quantifying muscle and joint forces over a broad range of weight bearing loads during exercise may provide data required to improve prosthetic materials and better protect against muscle and bone loss. Collectively, leg intramuscular pressure (IMP), ground reaction force (GRF), and the instrumented tibial tray force measurements provide a comprehensive assessment of leg muscle and joint biomechanical effects of gravity during exercise. Titration of body weight (BW) by lower body negative pressure (LBNP) and lower body positive pressure (LBPP) can reproducibly modulate IMP within leg muscle compartments. In addition, previous studies document peak tibial forces during various daily activities of 2.2 to 2.5 BW. The study objective was to determine the IMPs of the leg, axial compressive force on the tibia in vivo, vertical GRF, and knee range of motion during altered BW levels using LBPP and LBNP treadmill exercise. We hypothesize that peak GRF, peak tibial forces, and peak IMPs of the leg correlate linearly with percent BW, as generated across a broad range of upright LBPP and supine LBNP exercise. When running at 2.24 m/s the leg IMPs significantly increased over the loading range of 60% to 140% BW with LBPP and LBNP (P < 0.001); as expected, leg IMPs were significantly higher when running compared with standing (P < 0.001). During upright LBPP, total axial force at the knee increased linearly as a function of BW at 0.67 m/s (R(2) = 0.90) and 1.34 m/s (R(2) = 0.98). During supine LBNP, total axial force at the knee increased linearly as a function of BW at 0.67 m/s (R(2) = 0.98) and 1.34 m/s (R(2) = 0.91). The present study is the first to measure IMPs and peak tibial forces in vivo during upright LBPP, upright LBNP, and supine LBNP exercise. These data will aid the development of rehabilitation exercise hardware and prescriptions for patients and astronauts.