Impact of rocker sole footwear on plantar pressure distribution during standing and walking in adult obese women.

Purpose: Obesity increases the stresses applied to the foot. Ergonomic rocker sole shoes increase energy expenditure of standing and walking in obese individuals but could potentially alter plantar pressure distribution. The aim of this study was to compare plantar pressure distribution during standing and walking between rocker sole and flat-bottomed shoes in obese subjects.Methods: Twenty adult obese women were asked to stand quietly and to walk at their preferred walking speed whilst wearing flat-bottomed or rocker sole shoes. Plantar pressure distribution was assessed using instrumented insoles.Results: During standing, toe pressure and as well as midfoot force were higher with rocker sole than with flat-bottomed shoes (p < 0.05). During walking with rocker sole shoes, mean pressure and maximal force were lower under the toes and the forefoot, but higher under the midfoot and rearfoot regions with respect to flat-bottomed shoes (p < 0.05).Conclusions: While standing with rocker sole shoes, obese subjects showed augmented pressure under the toes whereas forefoot and heel pressure had no significant difference compared to the flat-bottomed shoes. As walking with rocker sole shoes resulted in decreased forces and pressures under the forefoot but increased overload at heel and midfoot regions, obese individuals may not benefit from wearing rocker sole shoes during walking, at least from a plantar pressure distribution perspective.Implications for rehabilitationThe use of ergonomic rocker sole shoes causes a redistribution of in-shoe plantar pressures leading to potentially detrimental adjustments that fail to attenuate the obesity-related increase in midfoot pressure during standing, while accentuating this region-specific impairment in dynamic conditions.Rocker sole shoes may best be avoided for walking in obese patients with heel pain or with any midfoot/rearfoot alteration such as medial arch flattening.

Reproducibility of clinician-friendly physical performance measures in individuals with obesity.

OBJECTIVE: To evaluate the reproducibility (reliability and agreement) of different physical performance measures in individuals with obesity. METHODS: Forty subjects (20 men, 20 women), mean age 29 years, mean body mass index (BMI) 42 kg/m2 completed several clinician-friendly performance-based tests (walking, stair-climbing, sit-to-stand, static balance, flexibility and strength) on 2 different occasions (test-retest design). Intraclass correlation coefficients (reliability) and smallest detectable changes (agreement) were calculated for each outcome measure. RESULTS: Intraclass correlation coefficients were relatively high (range 0.84-0.94) for all the performance-based measures (i.e. acceptable reliability). Smallest detectable changes were overall quite high and beyond the arbitrarily-defined minimal clinically important changes (i.e. poor agreement) for 3 out of 8 variables (sit-to-stand time, time-in-balance with eyes closed, and sit-and-reach distance). CONCLUSION: The clinician-friendly performance-based tests for individuals with obesity considered in this study appear legitimate for discriminative purposes, such as in cross-sectional studies. However, for longi-tudinal assessments (evaluative purposes), some measures should be used with greater caution due to limited agreement. Careful consideration should be given to the evaluation of physical performance in people with obesity, particularly in the context of conservative or surgical treatment for weight loss.

Respiratory muscle endurance training reduces the O2 cost of cycling and perceived exertion in obese adolescents.

In obesity, the increased O2 cost of breathing negatively affects the O2 cost of exercise and exercise tolerance. The purpose of the study was to determine whether, in obese adolescents, the addition of respiratory muscle endurance training (RMET) (isocapnic hyperpnea) to a standard body mass reduction program decreases the O2 cost of exercise and perceived exertion. Nine male obese adolescents [16.0 ± 1.4 yr (x ± SD), body mass 114.4 ± 22.3 kg] underwent 3 wk of RMET (5 days/week) in addition to a standard body mass reduction program. Eight age- and sex-matched obese adolescents underwent only the standard program (CTRL). Before and after interventions, patients performed on a cycle ergometer: incremental exercise; 12-min exercises at a constant work rate (CWR) of 65% and 120% at the gas exchange threshold (GET) determined before the intervention. Breath-by-breath pulmonary ventilation (V̇e) and O2 uptake (V̇o2), heart rate (HR), and ratings of perceived exertion for dyspnea/respiratory discomfort (RPER) and leg effort (RPEL) were determined. Body mass decreased (by ~3.0 kg) after both RMET (P = 0.003) and CTRL (P = 0.002). Peak V̇o2 was not affected by both interventions. Peak work rate was slightly, but significantly (P = 0.04), greater after RMET but not after CTRL. During CWR < GET, no changes were observed after both interventions. During CWR > GET, the O2 cost of cycling at the end of exercise (P = 0.02), the slope of V̇o2 vs. time (3-12 min) (P = 0.01), RPER (P = 0.01), and RPEL (P = 0.01) decreased following RMET, but not following CTRL. HR decreased after both RMET (P = 0.02) and CTRL (P = 0.03), whereas V̇e did not change. In obese adolescents RMET, superimposed on a standard body mass reduction program, lowered the O2 cost of cycling and perceived exertion during constant heavy-intensity exercise.

Computation of spatio-temporal parameters in level walking using a single inertial system in lean and obese adolescents.

In recent years, the availability of low-cost equipment capable of recording kinematic data during walking has facilitated the outdoor assessment of gait parameters, thus overcoming the limitations of three-dimensional instrumented gait analysis (3D-GA). The aim of this study is twofold: firstly, to investigate whether a single sensor on the lower trunk could provide valid spatio-temporal parameters in level walking in normal-weight and obese adolescents compared to instrumented gait analysis (GA); secondly, to investigate whether the inertial sensor is capable of capturing the spatio-temporal features of obese adolescent gait. These were assessed in 10 obese and 8 non-obese adolescents using both a single inertial sensor on the lower trunk and an optoelectronic system. The parameters obtained were not statistically different in either normal-weight or obese participants between the two methods. Obese adolescents walked with longer stance and double support phase compared to normal-weight participants. The results showed that the inertial system is a valid means of evaluating spatio-temporal parameters in obese individuals.

Foot-type analysis and plantar pressure differences between obese and nonobese adolescents during upright standing.

This study aimed to characterize the effect of obesity on foot-type and plantar pressure distribution in adolescents. Ten obese adolescents (obese group; BMI: 35.45±4.73 kg/m) and eight normal-weighted adolescents (control group; BMI: 18.67±2.46 kg/m) were recruited. Both groups were evaluated while standing using the Pedar-X in-shoe system. Foot-ground contact was characterized using contact area, peak of force and pressure calculated for the subareas of the foot. The analysis showed that obese participants had significantly higher area of contact in forefoot and midfoot (only in medial area) regions in comparison with the control group, whereas no statistically significant differences were observed for the rearfoot region. As far as the maximum pressure and force was concerned, similar results were obtained for both groups. Obese participants showed higher values for all the regions, with the exception of medial rearfoot area, for which the values were similar between the two groups. The analysis of foot-type distribution displayed that in the obese group high percentage of participants presented flat foot (70%) respect to cavus foot (20%) and normal foot (10%); on the contrary, in the control group, foot-types were markedly different, with 25% of participants with flat foot, 25% with cavus foot and 50% with normal foot. These results are important from a clinical perspective to develop and enhance the rehabilitative options in these patients and to avoid a worsening of their foot abnormalities. Untreated flat foot can in fact be disabling and over time can result in significant difficulties for the patient.

Acute respiratory muscle unloading by normoxic helium-O2 breathing reduces the O2 cost of cycling and perceived exertion in obese adolescents.

PURPOSE: In obesity, an increased work of breathing contributes to a higher O2 cost of exercise and negatively affects exercise tolerance. The purpose of the study was to determine whether, in obese adolescents, acute respiratory muscle unloading via normoxic helium-O2 breathing reduces the O2 cost of cycling and perceived exertion. METHODS: Nine males [age 16.8 ± 1.6 (x ± SD) years, body mass 109.9 ± 15.0 kg] performed on a cycle ergometer, breathing room air (AIR) or a 21 % O2-79 % helium mixture (He-O2): an incremental exercise, for determination of [Formula: see text]O2 peak and gas exchange threshold (GET); 12 min constant work rate (CWR) exercises at 70 % of GET (GET) determined in AIR. RESULTS: [Formula: see text]O2 peak was not different in the two conditions. From the 3rd to the 12th minute of exercise (both during CWR < GET and CWR > GET), [Formula: see text]O2 was lower in He-O2 vs. AIR (end-exercise values: 1.40 ± 0.14 vs. 1.57 ± 0.22 L min(-1) GET). During CWR > GET in AIR, [Formula: see text]O2 linearly increased from the 3rd to the 12th minute of exercise, whereas no substantial increase was observed in He-O2. The O2 cost of cycling was ~10 % (GET) lower in He-O2 vs. AIR. Heart rate and ratings of perceived exertion for dyspnea/respiratory discomfort and leg effort were lower in He-O2. CONCLUSIONS: In obese adolescents, acute respiratory muscle unloading via He-O2 breathing lowered the O2 cost of cycling and perceived exertion during submaximal moderate- and heavy-intensity exercise.

Feasibility study of detecting surface electromyograms in severely obese patients.

The aims of this study were to examine if surface EMG signals can be detected from the quadriceps femoris muscle of severely obese patients and to investigate if differences exist in quadriceps force and myoelectric manifestations of fatigue between obese patients and lean controls. Fourteen severely obese patients (body mass index, BMI, mean±SD: 44.9±6.3kg/m(2)) and fourteen healthy controls (BMI: 23.7±2.5kg/m(2)) were studied. The vastus medialis and lateralis of the dominant thigh were concurrently investigated during voluntary isometric contractions (10-s long at submaximal and maximal intensities and intermittent submaximal contractions until exhaustion) and sustained (120-s long) electrically elicited contractions. We found that the detection of surface EMG signals from the quadriceps is feasible also in severely obese subjects presenting increased thickness of the subcutaneous fat tissue. In addition, we confirmed and extended previous findings showing that the volume conductor properties determine the amplitude and spectral features of the detected surface EMG signals: the lower the subcutaneous tissue thickness, the higher the amplitude and mean frequency estimates. Further, we found no differences in the mechanical and myoelectric manifestations of fatigue during intermittent voluntary and sustained electrically elicited contractions between obese patients and lean controls.

Growth hormone-releasing effects of whole body vibration alone or combined with squatting plus external load in severely obese female subjects.

BACKGROUND: Whole body vibration (WBV) has been reported to exert growth hormone(GH)-releasing effects in healthy subjects. Despite the potential of WBV to positively affect body composition changes via lipolytic effects, few studies have been performed in obese subjects to date. METHODS: This study evaluated the acute effects of WBV alone or in combination with squatting plus external load (WBV+S) on serum GH levels and blood lactate concentrations in 7 severely obese women (age 22 ± 5 years; BMI 39.9 ± 2.9 kg/m2). RESULTS: WBV and WBV+S determined a significant GH increase (mean GH peaks 5.1 ± 1.9 ng/ml, p < 0.001 vs. basal, and 6.5 ± 3.7 ng/ml, p < 0.001 vs. basal, respectively), GH peaks occurring immediately after both exercise sessions. No significant differences were observed between GH peaks and GH net incremental area under the curve (nAUC) after both conditions (p = 0.39 and p = 0.53, respectively), the whole pattern of GH responsiveness being comparable among all the subjects. Lactate concentrations increased after both conditions (mean lactate peaks 2.0 ± 0.5 mmol/l, p < 0.05 vs. basal, and 4.5 ± 2.0 mmol/l, p < 0.001 vs. basal, respectively). The lactate response was significantly higher after WBV+S than after WBV (p < 0.05). Baseline GH and GH peak values positively correlated to baseline lactate and lactate peak concentrations in both conditions (R(2) = 0.64, p < 0.001, and R2 = 0.52, p < 0.05, respectively). CONCLUSIONS: WBV alone stimulates GH release and lactate production in severely obese female subjects, with no additive effect when combined with squatting plus external load. Further additional studies are required to verify the chronic effects of WBV exercise on the GH/IGF-1 system, which could represent a potentially effective approach for weight management in obese subjects.