Muscle activity during backward and forward running with body weight support

The combined influence of body weight support and running direction on self-selected movement patterns

We investigated metabolic costs, muscle activity, and perceptual responses during forward and backward running at matched speeds at different body weight support (BWS) conditions. Participants ran forward and backward on a lower body positive pressure treadmill at 0%BWS, 20%BWS, and 50%BWS conditions. We measured oxygen uptake, carbon dioxide production, heart rate, muscle activity, and stride frequency. Additionally, we calculated metabolic cost of transport. Furthermore, we used rating of perceived exertion and feeling scale to investigate perceptual responses. Feeling scale during running was higher with increasing BWS (0-50%BWS), regardless of running direction (p < 0.05). Oxygen uptake, heart rate, and metabolic cost of transport were influenced by the interaction of running direction and BWS (p < 0.01). For example, metabolic cost of transport during backward running was greater than when running forward only when running at 0%BWS (i.e., 4.4 ± 1.1 and 5.8 ± 1.4 J/kg/m for forward and backward running, respectively: p < 0.001). However, rectus femoris muscle activity, stride frequency, and rating of perceived exertion 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). We interpret our observations to indicate that environment (in the context of effective body weight) is a critical factor that determines self-selected movement patterns during forward and backward running.

Influence of speed on running strategies during forward and backward running with body weight support

BACKGROUND

Running with body weight support (BWS) and backward running have been included in exercise programs. However, it is not known how running characteristics of forward and backward running with BWS are influenced by the deviation in the running speed from the preferred speed (PS). The purpose of this study was to investigate how metabolic cost, muscle activity, and perceptual responses of forward and backward running with BWS are influenced by the deviation in running speed from the PS.

METHODS

Eleven participants ran forward and backward at 0%BWS, 20%BWS, and 50%BWS conditions. The running speed conditions were set to their mode-specific PS, PS+10%, and PS-10%. We measured metabolic cost, muscle activity, stride frequency, rating of perceived exertion, and feeling scale.

RESULTS

Metabolic cost, muscle activity (rectus femoris and gastrocnemius), and rating of perceived of exertion during running increased with increasing speed, regardless BWS and running direction (P<0.05). For example, a 10% increase in running speed from the PS produced averages of 7.1% and 7.7% increases in oxygen uptake and rectus femoris muscle activity, respectively. However, stride frequency during forward and backward running with BWS did not increase with increasing speed when running speed was manipulated around the PS (i.e., 10% increments: P>0.05), with the exception of forward running at 50%BWS.

CONCLUSIONS

A 10% increase in running speed from the PS may be useful for individuals who are required to increase their metabolic cost, muscle activity, and perceptual responses during running, regardless of BWS and running direction.

Role of Antigravity Training in Rehabilitation and Return to Sport After Running Injuries

Anti-gravity treadmill training is a therapeutic option to help recovering runners return to activity after injury. This current concept paper provides a synopsis of the latest evidence of the biomechanical and metabolic changes that occur with body weight support (BWS) treadmill training, effects of antigravity treadmill training on clinical outcomes and clinical case studies in injured runners. Literature searches identified studies with descriptive, experimental and interventional designs and case studies that examined acute and chronic use of antigravity treadmills in runners and relevant populations. Laboratory-based studies were included to provide technical considerations for rehabilitation programming. Antigravity treadmills use causes reductions in cadence, ground reaction forces (GRF), GRF impulses, knee and ankle range of motion, and vertical stiffness, with elevations in stride duration, flight time, ground contact time, and plantarflexion. Antigravity treadmills appear useful across a spectrum of injuries in runners, including postsurgical repair of osteochondral defect, stress reactions (medial tibia, pelvis), and lumbar disc herniation. Runners may preserve aerobic fitness, muscle activation patterns, and muscle mass during recovery compared to traditional rehabilitation protocols. Technical considerations for accurate loading include treadmill frame adjustment to appropriate height to ensure accuracy of level of BWS while running, and monitoring for fast cadence to ensure impact loading rates remain low. Speed or grade can be increased to maintain metabolic demand and fitness while minimizing bone and tissue loading. Monitoring for symptom provocation will guide protocol adjustments to BWS and prescriptions. Once able to run pain-free (sustained or interval) >95% BWS for >30 min, the runner is likely ready to safely transition to ground running. Antigravity treadmill training can be considered when available to facilitate smooth transition back to ground running in a conditioned state.

Identification of Tools for the Functional and Subjective Assessment of Patients in an Aquatic Environment: A Systematic Review

Aquatic therapy is one of the most common treatments for alleviating musculoskeletal pathologies. Its effectiveness has been evaluated with functional tests and questionnaires. Functional tests are used in aquatic therapy; however, in most cases, they are carried out in a non-aquatic environment and, as such, their results may differ from those of tests performed in an aquatic environment. A systematic review was performed to assess the accuracy of functional tests and patient-reported outcomes to assess aquatic therapy interventions. The authors conducted a literature search in July 2019. In total, 70,863 records were identified after duplicates removed. Of these, 14 records were included about functional tests assessment in aquatic environment and 725 records for questionnaires. The majority of the tests had also been assessed in a dry environment, allowing differences and similarities between the tests in the two environments to be observed. Different variables have been assessed in tests included in the present systematic review (cardiorespiratory, neuromuscular, kinematic, physiological, kinetic responses and rating of perceived exertion) which are included in the manuscript. Visual Analogue Scale, Western Ontario and McMaster Universities Osteoarthritis Index and the 12-item Short Form Health Survey were the assessments most commonly used by the different authors.

The effects of stride frequency manipulation on physiological and perceptual responses during backward and forward running with body weight support

PURPOSE

We investigated the influence of a change in stride frequency on physiological and perceptual responses during forward and backward running at different body weight support (BWS) levels.

METHODS

Participants ran forward and backward at 0% BWS, 20% BWS, and 50% BWS conditions on a lower body positive pressure treadmill. The stride frequency conditions consisted of forward and backward running at preferred stride frequency (PSF), PSF + 10%, and PSF-10%. We measured oxygen uptake ([Formula: see text]O₂), carbon dioxide production, heart rate (HR), muscle activity from the lower extremity, and rating of perceived exertion (RPE). Furthermore, we calculated the metabolic cost of transport (CoT).

RESULTS

[Formula: see text]O_2, HR, CoT, and muscle activity from the rectus femoris were significantly different between stride frequency conditions (P < 0.05). [Formula: see text]O₂, HR, and CoT during running at PSF + 10% were significantly higher than when running at PSF, regardless of running direction and BWS (P < 0.05). However, RPE was not different between stride frequency conditions (P > 0.05: e.g., 12.8-13.8 rankings in RPE for backward running at 0% BWS).

CONCLUSIONS

Manipulation of stride frequency during running may have a greater impact on physiological responses than on perceptual responses at a given speed, regardless of running direction and BWS. Individuals who need to increase their physiological demands during running may benefit from a 10% increase in stride frequency from the PSF, regardless of BWS and running direction.

Effect of 6-week retro or forward walking program on pain, functional disability, quadriceps muscle strength, and performance in individuals with knee osteoarthritis: a randomized controlled trial (retro-walking trial)

BACKGROUND

Previous studies reported the beneficial effects of walking in individual with mild to moderate knee osteoarthritis (OA). The current study aimed to compare the effect of 6-week retro versus forward walking program versus control group on pain, functional disability, quadriceps muscle strength and physical performance in individuals with knee OA.

METHODS

A three-arm single-blinded, randomized, controlled trial and intention-to-treat analysis was conducted in outpatient physiotherapy department, King Saud University, Saudi Arabia. Sixty-eight individuals (mean age, 55.6 years; 38 female) with knee OA participated. The participants in the retro or forward walking group completed 10 min of supervised retro or forward walking training in addition to usual care, 3 days/week for 6 weeks. The control group received a routine physiotherapy program. This program comprises a combination of closed and open kinematic chain exercises, including straight leg raising, isometric quadriceps, isometric hip adduction, terminal knee extension, semi-squat, and leg press. The primary outcomes were mean pain and knee function score measured by the numerical rating scale and the Western Ontario and McMaster Universities Osteoarthritis Index, respectively. The secondary outcomes were mean score of quadriceps muscle strength and timed up and go test scores. All the outcomes were analyzed at baseline and week 6.

RESULTS

In total, 68 subjects participated in this 6-week randomized, controlled trial. The completion rates of the primary and secondary outcome measures at week 6 were 91, 87, and 82% in the retro walking, forward walking, and control groups, respectively. In the intention-to-treat analysis, the retro walking group had a greater reduction in pain intensity (mean changes, 1.8 versus 1; p = 0.01) and functional disability (mean changes, 4.8 versus 2.2; p = 0.008) than the control group. Similarly, the retro walking group had a greater improvement in the quadriceps muscle strength (mean changes, 1.7 kg versus 0.7 kg; p = 0.008) and the timed up and go test (mean changes, 0.6 s versus 0.1 s; p = 0.003) than the control group.

CONCLUSIONS

The 6-week retro walking program compared with forward walking or control groups resulted in greater reduction in pain and functional disability and improved quadriceps muscle strength and performance in individuals with knee OA.

TRIAL REGISTRATION

Controlled Trials ISRCTN12850845 , Registered 26 January 2015.

Influence of stride frequency manipulation on muscle activity during running with body weight support

BACKGROUND

Running with body weight support (BWS) has been used for physical fitness enhancement. Nevertheless, gait mechanics of running with BWS is not fully understood.

RESEARCH QUESTION

We investigated influence of stride frequency manipulation on muscle activity during running at various BWS conditions.

METHODS

Nineteen participants (23.8 ± 4.1 years) ran on a lower body positive pressure treadmill at their preferred speed and preferred stride frequency (PSF) for 0%BWS, 50%BWS, and 80%BWS conditions. Preferred speed and PSF were selected for each of the BWS conditions. The stride frequency conditions consisted of running at PSF, PSF+10%, and PSF-10%. Muscle activity from the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GA) were measured.

RESULTS

RF and BF during running at the PSF+10% were higher than when running at the PSF, regardless of BWS (P < 0.01). Additionally, RF and TA during running at the PSF-10% were higher than when running at the PSF, regardless of BWS (P < 0.05). Furthermore, RF, TA, GA, and PSF during running decreased with increasing BWS (P < 0.05), although preferred speed increased with increasing BWS (P < 0.001).

SIGNIFICANCE

These observations suggest that manipulating stride frequency by 10% from the PSF during running produces greater RF, BF, and TA than when running at the PSF, regardless of BWS. Furthermore, it was suggested that a change in BWS influences RF, TA, GA, PSF, and preferred speed during running. Such information may be useful to enable the practitioner to refine the use of running with BWS in exercise programs.