Ankle Plantar Flexion Exercise Research Articles

The Immediate Effect of Cumulative Transverse Strain via Exercise on the Achilles Tendon in Individuals with and Without Flat Feet.

Flat feet change lower extremity alignment, and it may change the load distribution on Achilles tendon during exercise. The purpose of the present study was to investigate the immediate effect of cumulative transverse strain via resistive ankle plantarflexion exercise on the Achilles tendon in individuals with flat feet. Fourteen individuals with flat feet and 14 age-matched individuals with normal foot posture were enrolled in the present study. Achilles tendon thickness was measured by an ultrasonography device with a linear probe at 3 points: 1 cm (AT-1), 2 cm (AT-2), and 3 cm (AT-3) proximal to the superior aspect of the calcaneus. Ultrasonography measurements were performed before and after participants completed 90 repetitions of double-leg calf raise exercises which included moving the foot from full ankle dorsiflexion to full ankle plantarflexion. Achilles tendon thickness at all points measured was thinner in the flat feet group at both pre- and post-exercise conditions compared with that of the control group (p<0.05). Achilles tendon thickness at AT-1, AT-2, and AT-3 decreased after the exercise in both groups (p<0.001). The differences in Achilles tendon thickness at all points measured between pre- and post-exercise conditions were lower in individuals with flat feet than those of the control group (p<0.05). There was a significant decrease in Achilles tendon thickness after exercise in both groups; however, the tendon thickness markedly diminished in individuals with normal foot posture. The results are thought to result from changes in tendon structure and in load distribution on the Achilles tendon.

Deteriorated regional calf microcirculation measured by contrast-free MRI in patients with diabetes mellitus and relation with physical activity.

Objective:To evaluate regional calf muscle microcirculation in people with diabetes mellitus (DM) with and without foot ulcers, compared to healthy control people without DM, using contrast-free magnetic resonance imaging methods.Methods:Three groups of subjects were recruited: non-DM controls, DM, and DM with foot ulcers (DM + ulcer), all with ankle brachial index (ABI) > 0.9. Skeletal muscle blood flow (SMBF) and oxygen extraction fraction (SMOEF) in calf muscle were measured at rest and during a 5-min isometric ankle plantarflexion exercise. Subjects completed the Yale physical activity survey.Results:The exercise SMBF (ml/min/100 g) of the medial gastrocnemius muscle were progressively impaired: 63.7 ± 18.9 for controls, 42.9 ± 6.7 for DM, and 36.2 ± 6.2 for DM + ulcer, p < 0.001. Corresponding exercise SMOEF was the lowest in DM + ulcers (0.48 ± 0.09). Exercise SMBF in the soleus muscle was correlated moderately with the Yale physical activity survey (r = 0.39, p < 0.01).Conclusions:Contrast-free MR imaging identified progressively impaired regional microcirculation in medial gastrocnemius muscles of people with DM with and without foot ulcers. Exercise SMBF in the medial gastrocnemius muscle was the most sensitive index and was associated with HbA1c. Lower exercise SMBF in the soleus muscle was associated with lower Yale score.

Effects of low-load resistance exercise with blood flow restriction on high-energy phosphate metabolism and oxygenation level in skeletal muscle

We aimed to evaluate the effects of low-load resistance exercise with blood flow restriction (BFR) on high-energy phosphate metabolism, intracellular pH, and oxygenation level in the skeletal muscle. Seven males performed low-load ankle plantar flexion exercise (120 repetitions, 30% of one-repetition maximum) with and without BFR (130% of systolic blood pressure) inside a magnetic resonance device. Inorganic phosphate (Pi)-to-phosphocreatine (PCr) ratio, intracellular pH, and tissue oxygenation index (TOI) in the medial gastrocnemius were determined using 31P-magnetic resonance spectroscopy and near-infrared spectroscopy before and during exercise. The Pi-to-PCr ratio significantly increased during exercise in both conditions, with the BFR-condition values significantly exceeding the control-condition values. The BFR and control conditions showed significantly decreased intracellular pH during exercise, with the BFR-condition values being significantly lower than the control-condition values. The TOI significantly decreased during both exercises, but the decreases in the BFR condition were significantly greater than those observed in the control condition. Low-load BFR exercise places greater metabolic stress (greater PCr depletion, lower intracellular pH, and lower oxygenation level) on an exercising muscle than low-load non-restricted exercise.

Detection of Subclinical Peripheral Artery Ischemia in Healthy Male Smokers by an Ankle-Brachial Index After Exercise: Sasayama Study.

We investigated the relationship between smoking and the risk of nonnormal (≤0.99) ankle-brachial index (ABI) at rest and after ankle plantar flexion exercise in healthy male community dwellers. A cross-sectional study was performed including 228 Japanese men aged 40 to 64 years without a history of cardiovascular diseases. Participants were classified as never, ex-, and current smokers. We estimated the multivariate-adjusted odds ratios (ORs) for nonnormal ABI of ex- and current smokers in relation to never smokers after adjusting for age and other confounding factors. At rest, the prevalence of nonnormal ABI was not significantly different by smoking status. After exercise, the prevalence of nonnormal ABI increased from 1.8% to 11.5% in ex-smokers and from 3.8% to 17.0% in current smokers, while the prevalence did not significantly change in never smokers. The multivariate-adjusted OR for nonnormal ABI after ankle plantar flexion exercise, in relation to never smokers, was 3.85 (95% confidence interval [CI]: 0.79-18.9) for ex-smokers and 6.97 (95% CI: 1.32-36.7) for current smokers. Our results suggest that ABI after ankle plantar flexion exercise is useful for early detection of subclinical peripheral artery ischemia in male smokers without typical symptoms.

Effect of exercise-induced muscle damage on muscle hardness evaluated by ultrasound real-time tissue elastography.

PurposeTo assess the effect of exercise-induced muscle damage on muscle hardness and evaluate the relationship between muscle hardness and muscle damage indicators.MethodsSeven men (mean 25.3 years; 172.7 cm; 66.8 kg) performed the single-leg ankle plantar flexion exercise involving both concentric and eccentric contractions (10 sets of 40 repetitions). The hardness of the medial gastrocnemius (MG) was evaluated using ultrasound real-time tissue elastography before, from day 1 to 4, and day 7 after exercise. The strain ratio between the MG and a reference material was calculated. Simultaneously, we evaluated the magnetic resonance T2 value (an index of edema) of the triceps surae, the ankle dorsiflexion range of motion (ROM), and calf muscle soreness. Serum creatine kinase activity was assessed before, 2 and 4 h, and from day 1 to 4 after exercise.ResultsThe MG showed lower strain ratio, indicating increased muscle hardness, on day 4 post-exercise (P < 0.01) and higher T2 values on days 1–7 post-exercise (P < 0.01) relative to each pre-exercise value. The ankle dorsiflexion ROM was lower on days 2–4 post-exercise (P < 0.01). The serum creatine kinase markedly increased on days 3 and 4 post-exercise (not significant). The degree of muscle soreness among the post-exercise time points was similar. The decreased strain ratio did not correlate with the increased T2, the decreased joint ROM or muscle soreness.ConclusionMuscle hardness increased after strenuous resistance exercise, but the change was not related with muscle edema, decreased joint ROM, or muscle soreness resulting from muscle damage.

Repetitive Dorsi-Plantar Flexion Exercises in Ankle Joint have Effects on the Muscle Tones of Triceps, Vastus Medialis and Gastrocnemius

This study was designed to analyze repetitive dorsiflexion and plantarflexion exercises in ankles have effects on the muscle tones of triceps, vastus medialis and gastrocnemius. 25 healthy woman volunteers(ankle dorsiflexion exercise group: 13, ankle plantarflexion exercise group: 12) participated in the two ankle exercise models, which have performed 3 times a week for 3 weeks. Myotonometer was used to measure the muscle tones of the triceps, vastus medialis, gastrocnemius muscles, and measurements were performed before and after the application of the each exercise model. Repeated measured paired t-test and independent t-test was used to determine a statistical significance. The group of repetitive dorsiflexion exercise of the ankle have effects on the muscle tones of triceps, vastus medialis and gastrocnemius (p>.05). The group of repetitive plantarflexion exercise of the ankle have effects on the muscle tones of triceps, vastus medialis and gastrocnemius(p>.05). The groups of repetitive dorsiflexion and plantarflexion exercise of the ankle have effects on the muscle tones of triceps, vastus medialis and gastrocnemius(p>.05).

Conditioning of the Achilles tendon via ankle exercise improves correlations between sonographic measures of tendon thickness and body anthropometry

Although conditioning is routinely used in mechanical tests of tendon in vitro, previous in vivo research evaluating the influence of body anthropometry on Achilles tendon thickness has not considered its potential effects on tendon structure. This study evaluated the relationship between Achilles tendon thickness and body anthropometry in healthy adults both before and after resistive ankle plantarflexion exercise. A convenience sample of 30 healthy male adults underwent sonographic examination of the Achilles tendon in addition to standard anthropometric measures of stature and body weight. A 10-5 MHz linear array transducer was used to acquire longitudinal sonograms of the Achilles tendon, 20 mm proximal to the tendon insertion. Participants then completed a series (90-100 repetitions) of conditioning exercises against an effective resistance between 100% and 150% body weight. Longitudinal sonograms were repeated immediately on completion of the exercise intervention, and anteroposterior Achilles tendon thickness was determined. Achilles tendon thickness was significantly reduced immediately following conditioning exercise (t = 9.71, P < 0.001), resulting in an average transverse strain of -18.8%. In contrast to preexercise measures, Achilles tendon thickness was significantly correlated with body weight (r = 0.72, P < 0.001) and to a lesser extent height (r = 0.45, P = 0.01) and body mass index (r = 0.63, P < 0.001) after exercise. Conditioning of the Achilles tendon via resistive ankle exercises induces alterations in tendon structure that substantially improve correlations between Achilles tendon thickness and body anthropometry. It is recommended that conditioning exercises, which standardize the load history of tendon, are employed before measurements of sonographic tendon thickness in vivo.

MRI determination of muscle recruitment variations in dynamic ankle plantar flexion exercise.

The purpose of this study was to investigate the muscle recruitment variations in the dynamic ankle plantar flexion. A total of 17 subjects participated in this study and performed the ankle plantar flexion exercise. Magnetic resonance T2-weighted images were obtained from the calf before and immediately after exercise to calculate each T2 relaxation time in the medial and lateral gastrocnemius, soleus, tibialis posterior, flexor digitorum/hallucis longus, peroneus longus, and dorsiflexors. All the muscles except the dorsiflexors showed significantly increased T2 relaxation time and signal intensity on T2-weighted images after exercise. Above all, both gastrocnemius muscles showed significantly greater postexercise T2 relaxation time than the soleus, tibialis posterior, flexor digitorum/hallucis longus, and dorsiflexors. In addition, the peroneus longus had a tendency to show the greatest T2 relaxation time next to the gastrocnemius, but there was no significant difference between them. The present study may suggest that the gastrocnemius muscle, especially the medial side, was best recruited in the dynamic ankle plantar flexion exercise. In addition, it is possible that the peroneus longus was most recruited next to the gastrocnemius in this exercise mode.

NONINVASIVE ESTIMATION OF COOLING SKELETAL MUSCLE AFTER STRENUOUS EXERCISE

Cooling has been suggested to cause a decrease in cell metabolism and consequently allow the uninjured cells to survive the period of hypoxia, a reduction in the edema formation, and a relief in muscle soreness. However, these effects remain controversial. PURPOSE To estimate the effects of cooling skeletal muscle after exercise using 31P MR Specroscopy and MR Imaging. METHODS Male subjects (mean age ± SD, 23.8 ± 2.3 yr) were assigned to the normal (N=7) or the cooling group (N=7). Both groups performed the ankle plantar flexion exercise including eccentric contractions (12 repetitions, 5 sets). 15-min cold water immersion was administered to the subjects□f legs in the cooling group after exercise and initial post-exercise measurements. Intracellular pH was calculated from 31P-spectra of the medial gastrocnemius before, immediately, 30, 60 min, 24, 48, 96, and 168 h after exercise. T2-weighted images were obtained to calculate T2 relaxation times (T2) of the medial gastrocnemius before, 24, 48, 96, and 168 h after exercise. The muscle soreness level of the calf was also assessed at the same time as 31 P-spectra measurements. RESULTS Only control group showed significantly increased T2 from rest at 48 h post-exercise (p < 0.05). Intracellular pH significantly decreased immediately after exercise in both groups (p < 0.05). After that, the cooling group showed a significantly higher pH than the value at rest or the control group at 60 min post-exercise (p < 0.05). The soreness level significantly elevated immediately and at 24–48 h after exercise in both groups (p < 0.05). CONCLUSION Many studies reported that eccentric exercise resulted in delayed T2 elevation that would partly reflect the ultrastructual muscle damage accompanied by increased intramuscular water. Thus, this study may suggest that the cooling prevented the delayed edema and decreased the extent of muscle damage resulting from exercise. In addition, the cooling appears to have a positive effect on intracellular pH after exercise. Supported by the University of Tsukuba Research Project Grant.

In vivo muscle fibre behaviour during counter‐movement exercise in humans reveals a significant role for tendon elasticity

Six men performed a single ankle plantar flexion exercise in the supine position with the maximal effort with counter movement (CM, plantar flexion preceded by dorsiflexion) and without counter movement (NoCM, plantar flexion only) produced by a sliding table that controlled applied load to the ankle (40 % of the maximal voluntary force). The reaction force at the foot and ankle joint angle were measured using a force plate and a goniometer, respectively. From real-time ultrasonography of the gastrocnemius medialis muscle during the movement, the fascicle length was determined. The estimated peak force, average power, and work at the Achilles' tendon during the plantar flexion phase in CM were significantly greater than those in NoCM. In CM, in the dorsiflexion phase, fascicle length initially increased with little electromyographic activity, then remained constant while the whole muscle-tendon unit lengthened, before decreasing in the final plantar flexion phase. In NoCM, fascicle length decreased throughout the movement and the fascicle length at the onset of movement was longer than that of the corresponding phase in CM. It was concluded that during CM muscle fibres optimally work almost isometrically, by leaving the task of storing and releasing elastic energy for enhancing exercise performance to the tendon.

Muscle and tendon relations in humans: power enhancement in counter-movement exercise.

To clarify the mechanisms of power enhancement during counter-movement exercise, in vivo muscle fibre behavior during plantar flexion exercise was estimated by real time ultrasonography. Six healthy male subjects were requested to perform ankle plantar flexion exercise with counter-movement (CM, plantar flexion preceded by dorsiflexion) and without counter-movement (noCM, plantar flexion only) on a specially designed dynamometer. In CM, in the dorsiflexion phase, muscle fascicle length was initially lengthened, following which its length remained unchanged while the whole muscle-tendon unit was still lengthened, and decreased in the plantar flexion phase. In noCM, fascicle length decreased throughout the movement and it was longer at the onset of movement than in CM. During dorsiflexion phase in CM, muscle fascicles were not actively lengthened, but contracted isometrically at near optimum length of fibre; thus the increase in muscle-tendon unit length was taken up by elongation of the tendinous tissues. These results demonstrate that power enhancement during CM is due to higher force production by isometric contraction at optimal fibre length.

Cardiorespiratory kinetics during exercise of different muscle groups and mass in old and young.

The purpose was to compare cardiorespiratory kinetics during exercise of different muscle groups (double-leg cycling vs treadmill walking and single-leg ankle plantar flexion) in old and young subjects. Oxygen uptake (VO2) during exercise transitions was measured breath by breath, and the phase 2 portion of the response was fit by a monoexponential for determination of the time constant (tau) of VO2. Two separate studies were performed: in study 1, 12 old (age 66.7 yr) and 16 young (aged 26.3 yr) subjects were compared during cycling and ankle plantar flexion exercise, and in the study 2, five old (aged 69.6 yr) and five young (24.4 yr) subjects were compared during cycling and treadmill walking. VO2 transients during square-wave cycling exercise were significantly slower in the old compared with the young groups. In contrast, VO2 kinetics did not differ between old and young groups during plantar flexion exercise. Heart rate (HR) kinetics followed the same pattern, with tau HR being significantly slower in the old vs young groups during transitions to cycling but not to plantar flexion. In study 2 tau VO2 and tau HR during on-transients to treadmill square-wave exercise were significantly slower in the old group compared with the young group, but tau VO2 was significantly faster during treadmill exercise than during cycling in the old group. The differences with aging between the modes of exercise may be related to the muscle mass involved and the circulatory demands. On the other hand, slowed VO2 kinetics with age appear to occur in a mode (cycling) in which the muscles are not accustomed to the activity, whereas in a mode of normal activity (walking) and with the muscle groups (plantar flexors) accustomed to the activity, VO2 kinetics are not slowed to the same degree with age.

Kinetics of pulmonary oxygen uptake and muscle phosphates during moderate-intensity calf exercise.

The purpose of this study is to directly compare the dynamic responses of phosphocreatine (PCr) and P(i) to those oxygen uptake (VO2) measured at the lung during transitions to and from moderate-intensity exercise. Changes in PCr and P(i) were measured by 31P-nuclear magnetic resonance spectroscopy, and changes in VO2 were measured breath by breath by mass spectroscopy during transitions to and from moderate-intensity square-wave ankle plantar flexion exercise in 11 subjects (7 men and 4 women; mean age 27 yr). Three repeated transitions were averaged for improvement in signal-to-noise ratio of phosphate data, and 12 transitions were averaged for VO2 measurements. Averaged transitions were fit with a monoexponential curve for determination of the time constant (tau) of the responses. Mean tau values for on transients of PCr, P(i), and phrase 2 VO2 were 47.0, 57.7, and 44.5 s, respectively, whereas means tau values for off transients were 44.8, 42.1, and 33.4 s, respectively. There were no significant differences between tau values for phosphate- and VO2-measured transients or on and off transients. The similarity of on and off kinetics supports linear first-order respiratory control models. Measurement of phase 2 pulmonary VO2 kinetics to and from moderate-intensity small-muscle-mass exercise reflect muscle phosphate kinetics (and muscle oxygen consumption).