Walk-run transition in young and older adults: with special reference to the cardio-respiratory responses

A modified step-ramp-step protocol to prescribe constant-speed exercise in treadmill running

PURPOSE

This study investigated whether a running-adapted version of the cycling-based "step-ramp-step" (SRS) protocol would improve prediction of V ˙ O2 in treadmill exercise compared to the traditional prescriptive approach.

METHODS

Fourteen healthy individuals (6 females; 25 ± 6 years; 66.1 ± 12.7 kg) performed a treadmill-based SRS protocol including a ramp-incremental test to task failure followed by two constant-speed bouts within the moderate-(MODstep-below estimated lactate threshold; θLT), and heavy-intensity domains (HVYstep-between θLT and respiratory compensation point; RCP). Using the uncorrected V ˙ O2-to-speed relationship from the ramp exercise, three constant-speed bouts were performed at 40-50% between: baseline and θLT (CSEMOD); θLT and RCP (CSEHVY); and RCP and peak (CSESEV). For CSEMOD, CSEHVY, and CSESEV measured end-exercise V ˙ O2 was compared to predicted V ˙ O2 based on the: (i) "SRS-corrected" V ˙ O2-to-speed relationship (where MODstep and HVYstep were used to adjust the V ˙ O2 relative to speed); and (ii) linear "uncorrected" data.

RESULTS

Average treadmill speeds for CSEMOD and CSEHVY were 7.8 ± 0.8 and 11.0 ± 1.4 km·h-1, respectively, eliciting end-exercise V ˙ O2 of 1979 ± 390 and 2574 ± 540 mL·min-1. End-exercise V ˙ O2 values were not different compared to SRS-predicted V ˙ O2 at CSEMOD (mean difference: 5 ± 166 mL·min-1; p = 0.912) and CSEHVY (20 ± 128 mL·min-1; p = 0.568). The linear "uncorrected" estimates were not different for CSEMOD (- 91 ± 172 mL·min-1; p = 0.068) but lower for CSEHVY (- 195 ± 146 mL·min-1; p < 0.001). For CSESEV (running speed: 13.8 ± 1.7 km·h-1), the end-exercise V ˙ O2 was not different from peak V ˙ O2 achieved during the ramp (3027 ± 682 vs. 2979 ± 655 mL·min-1; p = 0.231).

CONCLUSION

In healthy individuals, the SRS protocol more accurately predicts speeds for a target V ˙ O2 compared to traditional approaches.

Cadence (steps/min) as an indicator of the walk-to-run transition

BACKGROUND

Humans naturally transition from walking to running at a point known as the walk-to-run transition (WRT). The WRT commonly occurs at a speed of ∼2.1 m/s (m/s) or a Froude number (dimensionless value considering leg length) of 0.5. Emerging evidence suggests the WRT can also be classified using a cadence of 140 steps/min. An accurate cadence-based WRT metric would aid in classifying wearable technology minute-level step metrics as walking vs. running.

PURPOSE

To evaluate performance of 1) WRT predictors directly identified from a treadmill-based dataset of sequentially faster bouts, and 2) accepted WRT predictors compiled from previous literature.

METHODS

Twenty-eight adults (71.4% men; age = 36.6 ± 12.8 years, BMI = 26.2 ± 4.7 kg/m2) completed a series of five-minute treadmill walking bouts increasing in 0.2 m/s increments until they freely chose to run. Optimal WRT values for speed, Froude number, and cadence were identified using receiver operating characteristic (ROC) curve analyses. WRT value performance was evaluated via classification accuracy metrics.

RESULTS

Overall accuracies (metric, percent) according to WRT predictors from previous literature were: speed (2.1 m/s, 55.0%), Froude number (0.5, 76.8%), and cadence (140 steps/min, 91.1%), and those from the dataset herein were: speed (1.9 and 2.0 m/s, 78.6%), Froude number (0.68, 77.3%), and cadence (134, 139, and 141 steps/min, 92.9%). The three equally accurate cadence values support a heuristic range of cadence-based WRT values in young and middle-aged adults: 135-140 steps/min.

SIGNIFICANCE

A tight range of cadence values performed better as WRT predictors compared to either previously reported or directly identified speed or Froude number values. These findings have important implications for gait classification, especially considering cadence is a simple metric which can be readily assessed across settings using direct observation or wearable technologies.

Serial vs. Integrated Outdoor Combined Training Programs for Health Promotion in Middle-Aged Males

The purpose of this study was to examine and compare the training and detraining effects of outdoor serial and integrated combined exercise programs on health, functional capacity, and physical fitness indices. Fifty-one untrained overweight/obese males (47 ± 4 years) were divided into a serial combined (SCG), an integrated combined (ICG), or a control (CG) group. The SCG and ICG implemented a 3-month training (3 sessions/week) consisting of walking and body weight exercises. The only difference between SCG and ICG was the sequence of aerobic and strength training. In SCG, the strength training was performed before aerobic training, while in ICG the aerobic and the strength training were alternated repeatedly in a predetermined order. Health, functional capacity, and physical fitness indices were measured before the training, following the termination of programs, and 1-month after training cessation. Following the training, both the SCG and ICG groups showed reduced blood pressure, heart rate, body fat, and waist-to-hip ratio (3−11%; p < 0.001), with improved respiratory function, muscle strength, aerobic capacity, flexibility, and balance (14−61%; p < 0.001). After 1-month of training cessation, significant reductions (p < 0.05) were observed in health indices and physical fitness without returning to baseline levels. However, there were no differences between SCG and ICG after training and training cessation (p > 0.05). In CG, all the above variables did not change. Furthermore, a great percentage of participants in both exercise groups (90%) reported high levels of enjoyment. In conclusion, both serial and integrated outdoor combined walking and body weight strength training programs are enjoyable and equally effective for improving health, functional capacity, and physical fitness indices in overweight/obese middle-aged males.

Changes Observed in the 6-minute Walk Test in Response to Exercise-based Cardiac Rehabilitation

Objectives: The six-minute walk test (6MWT) is widely used in exercise based cardiac rehabilitation (EBCR) for assessment of functional capacity. The purpose of this study was to assess the effect of structured exercise in an EBCR program on 6MWT change and to determine the significance of age, gender, body mass index (BMI), pathology and exercise attendance on influencing this outcome.Methods: Data from a single centre 6-week (twice weekly exercise and education of one-hour duration) exercise-based cardiac rehabilitation program were analysed. Between 2006 and 2019, 2524 patients (males 1923, females 601, mean age 63.5 ± 11.2 years) with cardiovascular disease completed a pre and post 6MWT. Analysis included the effect of age, gender, pathology, BMI and exercise attendance on 6MWT outcome.Results: The group mean improvement in the 6MWT was 21.8% (pre 6MWT 432 ± 83, post 6MWT 527 ± 102 metres). The age-related improvement showed that both males and females achieved a post 6MWT results equivalent to the pre 6MWT result of patients two decades younger with improvement in the 6MWT unrelated to exercise attendance.Conclusions: The 6MWT provides simple safe method for assessment of functional capacity in an out-of-hospital environment being suitable for all ages. The post EBCR 6MWT results showed a group mean improvement in excess of 20% for both sexes. The decline per decade in 6MWT distance is less than 20 metres up to the sixth decade with a more marked decline from the sixth to the eighth decade, the decline being approximately 40-metres for both sexes in the eighth decade.

Effect of 5 years of exercise training on the cardiovascular risk profile of older adults: the Generation 100 randomized trial

AIMS

The aim of this study was to compare the effects of 5 years of supervised exercise training (ExComb), and the differential effects of subgroups of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT), with control on the cardiovascular risk profile in older adults.

METHODS AND RESULTS

Older adults aged 70-77 years from Trondheim, Norway (n = 1567, 50% women), able to safely perform exercise training were randomized to 5 years of two weekly sessions of HIIT [∼90% of peak heart rate (HR), n = 400] or MICT (∼70% of peak HR, n = 387), together forming ExComb (n = 787), or control (instructed to follow physical activity recommendations, n = 780). The main outcome was a continuous cardiovascular risk score (CCR), individual cardiovascular risk factors, and peak oxygen uptake (VO2peak). CCR was not significantly lower [-0.19, 99% confidence interval (CI) -0.46 to 0.07] and VO2peak was not significantly higher (0.39 mL/kg/min, 99% CI -0.22 to 1.00) for ExComb vs. control. HIIT showed higher VO2peak (0.76 mL/kg/min, 99% CI 0.02-1.51), but not lower CCR (-0.32, 99% CI -0.64 to 0.01) vs. control. MICT did not show significant differences compared to control or HIIT. Individual risk factors mostly did not show significant between-group differences, with some exceptions for HIIT being better than control. There was no significant effect modification by sex. The number of cardiovascular events was similar across groups. The healthy and fit study sample, and contamination and cross-over between intervention groups, challenged the possibility of detecting between-group differences.

CONCLUSIONS

Five years of supervised exercise training in older adults had little effect on cardiovascular risk profile and did not reduce cardiovascular events.

REGISTRATION

ClinicalTrials.gov: NCT01666340.

Sarcopenia as a Mediator of the Effect of a Gerontogymnastics Program on Cardiorespiratory Fitness of Overweight and Obese Older Women: A Randomized Controlled Trial

The objectives were to analyze the effect of a gerontogymnastics program on functional ability and fitness on overweight and obese older woman and to understand if sarcopenia mediates its effect. This randomized controlled trial involved 216 overweight and obese women. The experimental group (EG) carried out 12 weeks of a gerontogymnastics program. The assessment was of gait speed, cardiorespiratory fitness, functional capacity, and muscle strength. EG showed significant improvements in almost every test. When the effect of training was adjusted by gait speed, the improvement of the 6 min walk test (MWT) for the trained group was no longer significant (p = 0.127). The improvement of the 6 MWT was significantly and positively associated with the 10 m test (β = −10.087). After including the 10-m test in the equations, the association between the 6MWT and carrying out the training program decreased but remained significant (β = −19.904). The mediation analysis showed a significant, direct and indirect effect with a significant Sobel test value (z = 6.606 ± 7.733; p = 0.000). These results indicate that a gerontogymnastics program improves functional capacity and fitness; and the effect of a gerontogymnastics program on CRF is mediated by sarcopenia in older women who are overweight and obese.

The Effects of Different Exergame Intensity Training on Walking Speed in Older Women

Objective: It is not known if the intensity in which exergames are performed can change gait parameters at different walking speeds. This study was designed to determine if a training program based on exergame exercises performed at different intensities (moderate vs. vigorous) influences walking speed and gait parameters in older adult women. Methods: After applying the inclusion criteria, 20 participants (69.5 ± 5.4 years) were randomized into two groups: moderate (11-13 perceived exertion) and vigorous (14-16 perceived exertion). Walking speed and gait parameters at self-selected walking speed (SSWS) and maximal walking speed (MWS) were evaluated before and after 3 months of exergame training. The walking speed and gait parameters were measured with an instrumented walkway. The walking speed reserve (WSR) was calculated as a difference and ratio. Results: There was pre-to-post effect of walking speed at self-selected walking pace (pre = 112.1 ± 16.4 cm.s^-1; post = 124.8 ± 16.4 cm.s^-1), in WSR calculated as ratio (pre = 1.35 ± 0.08; post = 1.28 ± 0.09), in a number of gait parameters at SSWS (step length, stride length, stride velocity, step time, stride time, swing time, stance time, single support, double support, gait cycle time, and cadence) and at MWS (step time, stride time, swing time, single support, double support, gait cycle time, and cadence). Conclusion: Irrespective of the exercise intensity, exergame training improved walking speed only at a self-selected walking pace and some gait parameters at self-selected and MWS in older women.

The role of plantigrady and heel-strike in the mechanics and energetics of human walking with implications for the evolution of the human foot

Human bipedal locomotion is characterized by a habitual heel-strike (HS) plantigrade gait, yet the significance of walking foot-posture is not well understood. To date, researchers have not fully investigated the costs of non-heel-strike (NHS) walking. Therefore, we examined walking speed, walk-to-run transition speed, estimated locomotor costs (lower limb muscle volume activated during walking), impact transient (rapid increase in ground force at touchdown) and effective limb length (ELL) in subjects (n=14) who walked at self-selected speeds using HS and NHS gaits. HS walking increases ELL compared with NHS walking since the center of pressure translates anteriorly from heel touchdown to toe-off. NHS gaits led to decreased absolute walking speeds (P=0.012) and walk-to-run transition speeds (P=0.0025), and increased estimated locomotor energy costs (P<0.0001) compared with HS gaits. These differences lost significance after using the dynamic similarity hypothesis to account for the effects of foot landing posture on ELL. Thus, reduced locomotor costs and increased maximum walking speeds in HS gaits are linked to the increased ELL compared with NHS gaits. However, HS walking significantly increases impact transient values at all speeds (P<0.0001). These trade-offs may be key to understanding the functional benefits of HS walking. Given the current debate over the locomotor mechanics of early hominins and the range of foot landing postures used by nonhuman apes, we suggest the consistent use of HS gaits provides key locomotor advantages to striding bipeds and may have appeared early in hominin evolution.

Physiological strain to prolonged exercise bouts at the walk-run transition speeds depends on locomotion mode in healthy untrained men

This study compared the physiological strain induced by prolonged walking and running performed at the walk-run transition speed (WRTS) in healthy untrained men. Twenty volunteers (age: 28 ± 5.01 years; height: 174.0 ± 0.3 cm; body mass: 74.5 ± 0.6 kg) underwent the following: (a) ramp-incremental maximal cardiopulmonary exercise test (CPET); (b) specific protocol to detect the WRTS; and (c) two 30-min walking and running bouts at WRTS (mean ± SD: 6.9 ± 0.06 km/h). Expired gases were collected during exercise bouts via the metabolic cart. A significant effect of locomotion mode (F = 4.8, P < 0.001) was observed with running resulting in higher cardiorespiratory responses than walking at the WRTS (oxygen uptake: mean difference = 0.26 L/min; pulmonary ventilation: mean difference = 5.53 L/min; carbon dioxide output: mean difference = 0.32 L/min; heart rate: mean difference = 13 beats/min; total energy expenditure: mean difference = 59 kcal). The rating of perceived exertion was similar across locomotion modes (mean difference = 0.3; P = 0.490). In conclusion, running promoted greater cardiorespiratory responses than walking at the WRTS in untrained healthy men. These data might have practical impact on aerobic training performed at intensities corresponding to WRTS.

Changes in the Preferred Transition Speed With Added Mass to the Foot

This study was conducted to investigate whether adding mass to subjects’ feet affects the preferred transition speed (PTS), and to ascertain whether selected swing phase variables (maximum ankle dorsiflexion angular velocity, angular acceleration, joint moment, and joint power) are determinants of the PTS, based upon four previously established criteria. After the PTS of 24 healthy active male subjects was found, using an incremental protocol in loaded (2 kg mass added to each shoe) and unloaded (shoes only) conditions, subjects walked at three speeds (60%, 80%, and 100% of PTS) and ran at one speed (100% of PTS) on a motor-driven treadmill while relevant data were collected. The PTS of the unloaded condition (2.03 ± 0.12 m/s) was significantly greater (P< .05) than the PTS of the loaded condition (1.94 ± 0.13 m/s). Within both load conditions, all dependent variables increased significantly with walking speed, decreased significantly when gait changed to a run, and were assumed to provide the necessary input to signal a gait transition, fulfilling the requirements of the first three criteria, but only ankle angular velocity reached a critical level before the transition, satisfying all four criteria to be considered a determinant of the PTS.

Validation of physical activity monitors in individuals with diabetes: energy expenditure estimation by the multisensor SenseWear Armband Pro3 and the step counter Omron HJ-720 against indirect calorimetry during walking

BACKGROUND

The purpose of this study is to test the agreement between energy expenditure estimate of the SenseWear(®) Armband Pro3 (SWA) (BodyMedia, Pittsburgh, PA) and the Omron HJ-720 (Omron Healthcare, Kyoto, Japan) step counter with indirect calorimetry (IC) as a gold standard in older individuals with type 1 and type 2 diabetes mellitus while walking on a treadmill.

SUBJECTS AND METHODS

In total, six men (60.3±3.1 years old) and 13 women (51.1±11.0 years old) with type 1 or type 2 diabetes mellitus were included in the study. Each subject performed three 15-min walking sessions with different combinations of speed and incline (3 km/h, 0%; 4 km/h, 0%; 5 km/h, 5%) on a treadmill. Energy expenditure (EE) was simultaneously measured by the SWA, Omron, and IC. Mean over-/underestimation and Pearson's correlation coefficients were used for statistical evaluation of the agreement between tested methods and IC.

RESULTS

At the speed of 3 km/h with 0% incline, mean overestimation of +81.19±23.81% was found for SWA (r=0.79, P<0.001) and +70.51±20.91% for Omron (r=0.77, P<0.001). At the speed of 4 km/h and 0% incline, mean overestimation found for SWA was +78.18±33.96% (r=0.63, P<0.01) and +75.77±33.36% for Omron (r=0.52, P<0.05). At the level of high-intensity exercise at the speed of 5 km/h and 5% incline, mean underestimation was -7.88±16.86% for SWA (r=0.74, P<0.001) and -7.37±16.07% for Omron (r=0.75, P<0.001).

CONCLUSIONS

Both methods led to considerable overestimation of calculated EE in level walking and a relatively minor underestimation during fast uphill walking.

Maximum walking speeds obtained using treadmill and overground robot system in persons with post-stroke hemiplegia

Background

Previous studies demonstrated that stroke survivors have a limited capacity to increase their walking speeds beyond their self-selected maximum walking speed (SMWS). The purpose of this study was to determine the capacity of stroke survivors to reach faster speeds than their SMWS while walking on a treadmill belt or while being pushed by a robotic system (i.e. “push mode”).

Methods

Eighteen chronic stroke survivors with hemiplegia were involved in the study. We calculated their self-selected comfortable walking speed (SCWS) and SMWS overground using a 5-meter walk test (5-MWT). Then, they were exposed to walking at increased speeds, on a treadmill and while in “push mode” in an overground robotic device, the KineAssist, until they were tested at a speed that they could not sustain without losing balance. We recorded the time and number of steps during each trial and calculated gait speed, average cadence and average step length.

Results

Maximum walking speed in the “push mode” was 13% higher than the maximum walking speed on the treadmill and both were higher (“push mode”: 61%; treadmill: 40%) than the maximum walking speed overground. Subjects achieved these faster speeds by initially increasing both step length and cadence and, once individuals stopped increasing their step length, by only increasing cadence.

Conclusions

With post-stroke hemiplegia, individuals are able to walk at faster speeds than their SMWS overground, when provided with a safe environment that provides external forces that requires them to attempt dynamic stability maintenance at higher gait speeds. Therefore, this study suggests the possibility that, given the appropriate conditions, people post-stroke can be trained at higher speeds than previously attempted.

Assessment of Cardiorespiratory Fitness without Exercise in Elderly Men with Chronic Cardiovascular and Metabolic Diseases

Low cardiorespiratory (CRF) is associated with health problems in elderly people, especially cardiovascular and metabolic disease. However, physical limitations in this population frequently preclude the application of aerobic tests. We developed a model to estimate CRF without aerobic testing in older men with chronic cardiovascular and metabolic diseases. Subjects aged from 60 to 91 years were randomly assigned into validation (n = 67) and cross-validation (n = 29) groups. A hierarchical linear regression model included age, self-reported fitness, and handgrip strength normalized to body weight (R² = 0.79; SEE = 1.1 METs). The PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage in relation to the original model and that predicted by the model and actual CRF correlated well in the cross-validation group (r = 0.85). The area under curve (AUC) values suggested a good accuracy of the model to detect disability in the validation (0.876, 95% CI: 0.793–0.959) and cross-validation groups (0.826, 95% CI: 0.677–0.975). Our findings suggest that CRF can be reliably estimated without exercise test in unhealthy elderly men.

Walk-run transition speed training as an efficient exercise adjunct to dietary restriction in the management of obesity: a prospective intervention pilot study

OBJECTIVE

The aim of this study was to test the utility of preferred walk-run transition speed (WRTS) in exercise training adjunct to dietary restriction for obesity management in healthy obese women.

MATERIALS AND METHODS

37 obese women (age: 35 ± 9 years, body mass index (BMI): 34.9 ± 4.6 kg/m(2)) were assigned to an intervention pilot study during 6 months of restricted diet alone (RD) followed by 6 months of RD combined with WRTS (RD and WRTS) as a training exercise. Body mass, waist circumference (WC), fat mass (FM), fat free mass (FFM), active cell mass (ACM), fasting glucose, serum lipids (triacylglycerol (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), apo-lipoproteins A1 (ApoA1) and B (ApoB)], leptin and insulin concentrations, and HOMA-IR were assessed at baseline (T0), at the end of the RD alone (T1), and at the end of the RD and WRTS programme (T2).

RESULTS

Mean weight loss was 8.6 ± 4.9 kg and 2.2 ± 2.9 kg for (T0-T1) and (T1-T2), respectively. Significant BMI and WC reductions were reported at T1 and T2. FM decreased significantly both with RD and with RD and WRTS training whereas FFM and ACM increased with RD and WRTS training only. TG decreased significantly with the two phases of the programme. A significant increase in HDL-C, and a decrease in LDL-C and TC/HDL-C ratio were noticed with RD and WRTS training. Heart rate monitored in training improved significantly after RD and WRTS training. A significant relationship (r = 0.542, p < 0.02) was demonstrated between reductions in serum leptin and insulin concentrations observed with both RD and WRTS training.

CONCLUSION

The addition of WRTS training to RD promoted a greater reduction in body mass, WC, FM, leptin and insulin concentrations, improved metabolic and cardiovascular risk factors, and enhanced cardiovascular fitness.