Replacing saturated fatty acids with polyunsaturated fatty acids increases the abundance of Lachnospiraceae and is associated with reduced total cholesterol levels-a randomized controlled trial in healthy individuals.

BACKGROUND: Improving dietary fat quality strongly affects serum cholesterol levels and hence the risk of cardiovascular diseases (CVDs). Recent studies have identified dietary fat as a potential modulator of the gut microbiota, a central regulator of host metabolism including lipid metabolism. We have previously shown a significant reduction in total cholesterol levels after replacing saturated fatty acids (SFAs) with polyunsaturated fatty acids (PUFAs). The aim of the present study was to investigate the effect of dietary fat quality on gut microbiota, short-chain fatty acids (SCFAs), and bile acids in healthy individuals. In addition, to investigate how changes in gut microbiota correlate with blood lipids, bile acids, and fatty acids. METHODS: Seventeen participants completed a randomized, controlled dietary crossover study. The participants received products with SFAs (control) or PUFAs in random order for three days. Fecal samples for gut microbiota analyses and fasting blood samples (lipids, fatty acids, and bile acids) were measured before and after the three-day intervention. RESULTS: Of a panel of 40 bacteria, Lachnospiraceae and Bifidobacterium spp. were significantly increased after intervention with PUFAs compared with SFAs. Interestingly, changes in Lachnospiraceae, as well as Phascolarlactobacterium sp. and Eubacterium hallii, was also found to be negatively correlated with changes in total cholesterol levels after replacing the intake of SFAs with PUFAs for three days. No significant differences in SCFAs or bile acids were found after the intervention. CONCLUSION: Replacing SFAs with PUFAs increased the abundance of the gut microbiota family of Lachnospiraceae and Bifidobacterium spp. Furthermore, the reduction in total cholesterol after improving dietary fat quality correlated with changes in the gut microbiota family Lachnospiraceae. Future studies are needed to reveal whether Lachnospiraceae may be targeted to reduce total cholesterol levels. TRIAL REGISTRATION: The study was registered at Clinical Trials ( https://clinicaltrials.gov/ , registration identification number: NCT03658681).

Reported Outcome Measures in Studies of Real-World Ambulation in People with a Lower Limb Amputation: A Scoping Review.

BACKGROUND: The rapidly increasing use of wearable technology to monitor free-living ambulatory behavior demands to address to what extent the chosen outcome measures are representative for real-world situations. This scoping review aims to provide an overview of the purpose of use of wearable activity monitors in people with a Lower Limb Amputation (LLA) in the real world, to identify the reported outcome measures, and to evaluate to what extent the reported outcome measures capture essential information from real-world ambulation of people with LLA. METHODS: The literature search included a search in three databases (MEDLINE, CINAHL, and EMBASE) for articles published between January 1999 and January 2022, and a hand-search. RESULTS AND CONCLUSIONS: 98 articles met the inclusion criteria. According to the included studies' main objective, the articles were classified into observational (n = 46), interventional (n = 34), algorithm/method development (n = 12), and validity/feasibility studies (n = 6). Reported outcome measures were grouped into eight categories: step count (reported in 73% of the articles), intensity of activity/fitness (31%), type of activity/body posture (27%), commercial scores (15%), prosthetic use and fit (11%), gait quality (7%), GPS (5%), and accuracy (4%). We argue that researchers should be more careful with choosing reliable outcome measures, in particular, regarding the frequently used category step count. However, the contemporary technology is limited in providing a comprehensive picture of real-world ambulation. The novel knowledge from this review should encourage researchers and developers to engage in debating and defining the framework of ecological validity in rehabilitation sciences, and how this framework can be utilized in the development of wearable technologies and future studies of real-world ambulation in people with LLA.

Beneficial effect on serum cholesterol levels, but not glycaemic regulation, after replacing SFA with PUFA for 3 d: a randomised crossover trial.

Replacing intake of SFA with PUFA reduces serum cholesterol levels and CVD risk. The effect on glycaemic regulation is, however, less clear. The main objective of the present study was to investigate the short-term effect of replacing dietary SFA with PUFA on glycaemic regulation. Seventeen healthy, normal-weight participants completed a 25-d double-blind, randomised and controlled two-period crossover study. Participants were allocated to either interventions with PUFA products or SFA products (control) in a random order for three consecutive days, separated by a 1·5-week washout period between the intervention periods. Glucose, insulin and TAG were measured before and after an oral glucose tolerance test. In addition, fasting total cholesterol, NEFA and plasma total fatty acid profile were measured before and after the 3-d interventions. Fasting and postprandial glucose, insulin, and TAG levels and fasting levels of NEFA and plasma fatty acid profile did not differ between the groups. However, replacing dietary SFA with PUFA significantly reduced total cholesterol levels by 8 % after 3 d (P = 0·002). Replacing dietary SFA with PUFA for only 3 d has beneficial cardio-metabolic effects by reducing cholesterol levels in healthy individuals.

Human skeletal muscle fiber type percentage and area after reduced muscle use: A systematic review and meta-analysis.

The main objective of this systematic review was to examine the effect of reduced muscle activity on the relative number of type 1 muscle fibers (%) in the human vastus lateralis muscle. Other objectives were changes in type 2A and 2X percentages and muscle fiber cross-sectional area. We conducted systematic literature searches in eight databases and included studies assessing type 1 fiber percentage visualized by ATPase or immunohistochemical staining before and after a period (≥14 days) of reduced muscle activity. The reduced muscle activity models were detraining, leg unloading, and bed rest. Forty-two studies comprising 451 participants were included. Effect sizes were calculated as the mean difference between baseline and follow-up and Generic Inverse Variance tests with random-effects models were used for the weighted summary effect size. Overall, the mean type 1 muscle fiber percentage was significantly reduced after interventions (-1.94%-points, 95% CI [-3.37, -0.51], P = .008), with no significant differences between intervention models (P = .86). Meta-regression showed no effect of study duration on type 1 fiber percentage (P = .98). Conversely, the overall type 2X fiber percentage increased after reduced muscle activity (P < .001). The CSA of the muscle fiber types decreased after the study period (all P-values < 0.001) with greater reductions in type 2 than type 1 fibers (P < .001). The result of this meta-analysis display that the type 1 muscle fiber percentage decrease as a result of reduced muscle activity, although the effect size is relatively small.

The physiological responses to repeated upper-body sprint exercise in highly trained athletes.

PURPOSE: To study performance, physiological and biomechanical responses during repeated upper-body sprint exercise. METHODS: Twelve male elite cross-country skiers performed eight 8-s maximal poling sprints with a 22-s recovery while sitting on a modified SkiErg poling ergometer. Force, movement velocity, cycle rate, work per cycle, oxygen saturation in working muscles and pulmonary oxygen uptake were measured continuously. A 3-min all-out ergometer poling test determined VO2peak, and 1 repetition maximum (1RM) strength was determined in a movement-specific pull-down. RESULTS: Average sprint power was 281 ± 48 W, with the highest power on the first sprint, a progressive decline in power output over the following four sprints, and a sprint decrement of 11.7 ± 4.1 %. Cycle rate remained unchanged, whereas work per cycle progressively decreased (P < 0.05). m. triceps brachii and m. latissimus dorsi were highly desaturated already after the first sprint (all P < 0.05), whereas the response was delayed for m. biceps brachii and m. vastus lateralis. Correspondingly, increases in VO2 mainly occurred over the first two sprints (P < 0.05) and plateaued at approximately 75 % of VO2peak. 1RM correlated with power during the first four sprints and with average sprint power (r = 0.71-0.80, all P < 0.05), whereas VO2peak correlated with power in the last three sprints (r = 0.60-0.71, all P < 0.05). CONCLUSIONS: The main decrement in upper-body sprint performance was evident in the first five sprints, followed by highly desaturated muscles and a plateau in pulmonary oxygen uptake already after the first 2-3 sprints. While high maximal strength seems important for producing power, aerobic capacity correlates with power in the last sprints.

Four weeks of inpatient comprehensive prosthetic rehabilitation achieves contrasting results in different groups of prosthetic users.

BACKGROUND: This study explored how inpatient exercise rehabilitation affected prosthetic mobility, function, and ambulation in persons with lower limb loss. METHODS: In this explorative prospective nonrandomized intervention study, experienced (EXP-INT, n = 20) and new prosthetic users (NEW-INT, n = 18) completed a 4-week rehabilitation intervention. A control group of experienced prosthetic users (n = 19) received no intervention. Tests were performed at baseline (pretest) and after 4 weeks (posttest). A step-monitoring device recorded ambulatory activity. RESULTS: For the primary outcome measure, Prosthetic Limb Users Survey of Mobility, the between-group analysis revealed significant differences (χ2 = 10.91, df = 2, p < 0.01). Within-group Prosthetic Limb Users Survey of Mobility T-scores improved by 8.1% for the EXP-INT (p < 0.01) and 15.1% for NEW-INT (p < 0.01). Significant between-group differences were observed for the Amputee Mobility Predictor, L-test, 2-minute walk test, and 10-meter walk test. Within-group analysis demonstrated nonsignificant changes for the EXP-INT except for Prosthetic Limb Users Survey of Mobility, while the NEW-INT improved by 24.1% (p < 0.001), 34.0% (p < 0.01), 46.5% (p < 0.05), and 31.0% (p < 0.01), respectively. The number of steps during the last 7 d of rehabilitation showed significant differences between the groups (χ2 = 13.99, df = 2, p < 0.001). The NEW-INT improved by 138% (p < 0.05) compared with the first 7 d of rehabilitation, while the EXP-INT had nonsignificant changes. CONCLUSIONS: A 4-week rehabilitation intervention substantially increased prosthetic mobility, function, and ambulation activity for new prosthetic users but less so for experienced users. The results of the NEW-INT at discharge signify a considerable functional improvement.

Energy expenditure during typical household and community activities of daily living in persons with lower limb amputation: A pilot study.

INTRODUCTION: Knowledge about the energy expenditure of typical activities of daily living (ADL) in persons with lower limb amputation (LLA) is lacking. This study investigated the following: (1) oxygen consumption per unit distance (V̇O2; mL·kg-1·min-1), (2) proportion utilization of peak oxygen consumption (%V̇O2peak), (3) oxygen cost (energy cost; mL·kg-1·m-1), and (4) perceived exertion (rating of perceived exertion) of ADL in persons with LLA and able-bodied controls. METHODS: Participants (21 with LLA/12 controls) performed 2 household ADL experiments: in-house walking and vacuuming and 3 community ADL experiments: marked shopping, fast walking, and stair negotiation. V̇O2peak was assessed with arm crank ergometry, and ambulatory activity was monitored for 7 days with a StepWatch. RESULTS: Participants with LLA performed in-house walking, marked shopping, vacuuming, and stair negotiation at a similar V̇O2 as controls, while their self-selected walking speed (WS) was significantly lower. Participants with LLA had significantly higher %V̇O2peak than controls during in-house walking and reported a significantly higher rating of perceived exertion for vacuuming and marked shopping. The highest possible WS of participants with LLA during fast walking was significantly lower than that of controls, but V̇O2 was also significantly lower, indicating a limited capacity to walk at higher WS. Participants with LLA had a significantly lower daily step count, significantly lower-proportion high-intensity ambulation, but significantly higher-proportion low-intensity ambulation than controls, indicating that persons with LLA also walked at lower WS in daily life. CONCLUSIONS: The results indicate that persons with LLA have increased physical and perceived effort during performance of ADL compared with persons without amputation, which has consequences for community participation, and hence independence and quality of life.

Impact of the COVID-19 restrictions on physical activity and quality of life in adults with lower limb amputation.

BACKGROUND: This study investigated the impact of COVID-19 restrictions on ambulatory activity and health-related quality of life (HR-QoL) in people with a lower limb amputation (LLA) in Norway. We hypothesized that the restrictions would negatively affect HR-QoL and decrease prosthetic wear time and ambulatory activity in participants with already limited mobility. METHODS: Twenty individuals with LLA (age and time since amputation 56.2 ± 11.9 and 22.3 ± 20.1 years, respectively) participated. Ambulatory activity (stepwatch: prosthetic wear time; steps per day; minutes of low-intensity (1-15 steps min-1), moderate-intensity (16-40 steps min-1), and high-intensity ambulation (>40 steps min-1)) and HR-QoL (EQ-5D-5L) data were collected prepandemic and 8-12 months later during pandemic restrictions. Semistructured interviews identified personal experiences of coping with restrictions. RESULTS: Prosthetic wear time decreased significantly (-1.0 ± 1.5 hours day-1, p < 0.05). Steps per day (440 ± 1481), moderate-intensity and high-intensity ambulation (3.7 ± 23.4, and 4.8 ± 13.9 minutes day-1, respectively), and EQ-5D-5L index (.02 ± .10) increased, whereas low-intensity ambulation decreased (-1.5 ± 16.1 minutes day-1), all nonsignificant changes. Qualitative analysis identified three themes related to coping with restrictions: (1) personal situation, (2) a prosthetic user's perspective, and (3) mindset. CONCLUSIONS: Increased time spent at home might explain the decreased prosthetic wear time. Contrary to the hypothesis, participants did not decrease their physical activity, and the declined low-intensity ambulation was offset by increased moderate-intensity and high-intensity ambulation. A positive mindset, intrinsic motivation, and health awareness may be important factors for maintaining ambulatory activity and HR-QoL in people with LLA.

Effect of Manual Wheelchair Type on Mobility Performance, Cardiorespiratory Responses, and Perceived Exertion.

This study is aimed at comparing the design and configuration of the most commonly used manual wheelchair models through cardiorespiratory responses, perceived exertion, and mobility performance using two different manual wheelchairs, during mobility tasks. A within-group 2 × 3 × 2 controlled experiment was designed with three independent and four dependent variables. The independent variables included wheelchairs, with the levels active wheelchair with a rigid frame and passive wheelchair with foldable frame; conditions with the levels straight line, slalom, and agility; and speed with levels comfortable and fast. Dependent variables included oxygen uptake (VO2), distance travelled, speed, and perceived exertion. Results show that the active wheelchair yielded more beneficial characteristics although only the effect of wheelchair type on VO2 efficiency (oxygen uptake per meter travelled) was statistically significant with a large effect size (F(1, 14) = 118.298, p < 0.001, η 2 = 0.541). The better VO2 efficiency was achieved with the active wheelchair under all tested conditions. The effect of wheelchair type on Borg scores was also statistically significant, although with a small effect size (F(1, 14) = 10.340, p = 0.006, η 2 = 0.119); thus, active wheelchair use had lower Borg scores under all trials and was considered less exhausting than the passive wheelchair. In summary, use of the active wheelchair resulted in the users expending less energy per meter travelled and at the same time experiencing less fatigue. This may benefit overall wheelchair mobility and possibly reduce health complications.

Increased prefrontal cortical activation during challenging walking conditions in persons with lower limb amputation - an fNIRS observational study.

Background: Lower limb amputation (LLA) alters the sensorimotor control systems. Despite the self-reports of increased attention during mobility, the interaction between mobility and cognitive control mechanisms is not fully understood.Objective: Concurrently evaluate walking performance and prefrontal cortical (PFC) activity in persons with and without LLA during different walking conditions.Methods: Thirty-nine persons with LLA and thirty-three able-bodied controls participated. Walking performance was evaluated using the Figure-of 8-walk-test during three conditions: 1) UW (Usual walking with self-selected walking speed); 2) WCT (walking and carrying a tray with two cups filled with water); and 3) WUT (walking on uneven terrain). PFC activity was assessed using functional near-infrared spectroscopy (fNIRS). Linear mixed models were used to detect changes between groups and between walking conditions within each group.Results: Between-group comparisons showed increased PFC activity in persons with LLA during UW and WUT, and a significant decrease in walking performance during WCT and WUT compared to controls. Within-group comparisons showed increased PFC activity during WUT compared with UW and WCT and an overall difference in walking performance between the conditions (WU > WUT > WCT) in both groups. However, the effect of walking condition on PFC activity and walking performance was not modified by group (P > .1).Conclusion: The results suggest that persons with LLA have increased attentional demands during walking but choose the same cognitive-mobility strategy during challenging walking conditions as able-bodied persons. However, the attentional demands seem to depend on the complexity of the task.

Gut microbiota is associated with dietary intake and metabolic markers in healthy individuals.

Background: Metabolic diseases have been related to gut microbiota, and new knowledge indicates that diet impacts host metabolism through the gut microbiota. Identifying specific gut bacteria associated with both diet and metabolic risk markers may be a potential strategy for future dietary disease prevention. However, studies investigating the association between the gut microbiota, diet, and metabolic markers in healthy individuals are scarce. Objective: We explored the relationship between a panel of gut bacteria, dietary intake, and metabolic and anthropometric markers in healthy adults. Design: Forty-nine volunteers were included in this cross-sectional study. Measures of glucose, serum triglyceride, total cholesterol, hemoglobin A1c (HbA1c), blood pressure (BP), and body mass index (BMI) were collected after an overnight fast, in addition to fecal samples for gut microbiota analyzes using a targeted approach with a panel of 48 bacterial DNA probes and assessment of dietary intake by a Food Frequency Questionnaire (FFQ). Correlations between gut bacteria, dietary intake, and metabolic and anthropometric markers were assessed by Pearson's correlation. Gut bacteria varying according to dietary intake and metabolic markers were assessed by a linear regression model and adjusted for age, sex, and BMI. Results: Of the 48 gut bacteria measured, 24 and 16 bacteria correlated significantly with dietary intake and metabolic and/or anthropometric markers, respectively. Gut bacteria including Alistipes, Lactobacillus spp., and Bacteroides stercoris differed according to the intake of the food components, fiber, sodium, saturated fatty acids, and dietary indices, and metabolic markers (BP and total cholesterol) after adjustments. Notably, Bacteroides stercoris correlated positively with the intake of fiber, grain products, and vegetables, and higher Bacteroides stercoris abundance was associated with higher adherence to Healthy Nordic Food Index (HNFI) and lower diastolic BP after adjustment. Conclusion: Our findings highlight the relationship between the gut microbiota, diet, and metabolic markers in healthy individuals. Further investigations are needed to address whether these findings are causally linked and whether targeting these gut bacteria can prevent metabolic diseases.

Relationship between level of daily activity and upper-body aerobic capacity in adults with a lower limb amputation.

BACKGROUND: Previous studies show that people with lower limb amputation (LLA) have a sedentary lifestyle, reduced walking capacity, and low cardiorespiratory fitness (VO2peak). There is, however, no knowledge on the relationship between cardiorespiratory fitness and objectively measured level of physical activity in daily life. OBJECTIVES: To investigate the relationship between upper-body VO2peak, physical activity levels, and walking capacity in persons with LLA. STUDY DESIGN: Correlational and descriptive study. METHODS: Fourteen participants with LLA performed an assessment of VO2peak on an arm-crank ergometer and walking capacity (preferred walking speed and 2-minute walking test). Level of physical activity was measured over 7 days with a step activity monitor (number of steps; sedentary time; and proportion of low-intensity, moderate-intensity, high-intensity, and peak-intensity activity level). RESULTS: VO2peak correlated significantly with number of steps per day (r = 0.696, p = 0.006), sedentary time (r = -0.618, p = 0.019), high-intensity activity level (r = 0.769, p = 0.001), and peak-intensity activity level (r = 0.674, p = 0.008). After correcting for age, correlations were still large and significant. Large correlations were also found between VO2peak, preferred walking speed (r = 0.586, p = 0.027), and 2-minute walking test (r = 0.649, p = 0.012). CONCLUSIONS: We provide the first evidence of the strong relationships between upper-body VO2peak, sedentary behavior, high-intensity activity level, and walking capacity in persons with LLA. Further research is needed to investigate the potential effect of upper-body cardiorespiratory fitness on the level of activity in daily life, or vice versa.

Assessing mobility for persons with lower limb amputation: the Figure-of-Eight Walk Test with the inclusion of two novel conditions.

PURPOSE: To investigate the internal consistency, convergent and known-groups construct validity of the Figure-of-Eight Walk Test with two novel conditions in persons with lower limb amputation, and to examine differences in walking performance between the three conditions within a group of persons with transtibial amputation and transfemoral amputation/knee disarticulation. MATERIALS AND METHODS: Fifty adults with unilateral amputation participated, 28 of whom had undergone a transtibial amputation and 22 a transfemoral amputation/knee disarticulation. Three Figure-of-Eight Walk Test conditions were investigated: 1) walking at a self-selected walking speed, 2) walking while carrying a tray with two cups of water, and 3) walking on uneven terrain. Internal consistency was evaluated using Cronbach's alpha. Convergent construct validity was examined by analysing the relationship between the Figure-of-Eight Walk Test parameters and performance-based parameters (Amputee Mobility Predictor, Ten-Meter Walk Test, Six-Minute Walk Test) and self-report measures (Prosthetic Limb Users Survey of Mobility, Activities-specific Balance Confidence Scale) using Spearman's rank-order correlations. Known-groups construct validity was assessed by comparing the Figure-of-Eight Walk Test parameters based on anatomical level of amputation. Friedman's test and post hoc analysis were used to examine differences between the walking conditions within each group. RESULTS: Cronbach's alpha coefficients of the Figure-of-Eight Walk Test parameters for all three conditions ranged from 0.89 to 0.99. The Figure-of-Eight Walk Test time and step parameters demonstrated moderate to good correlation (ρ = -0.50 to -0.77) for performance-based mobility measures. The correlations were stronger during Condition 3 in comparison with the original Figure-of-Eight Walk Test. The correlation was fair to good (ρ = -0.41 to -0.57) for the self-report mobility measures. Comparison between groups showed a difference between transtibial and transfemoral amputation/knee disarticulation participants when it comes to the Figure-of-Eight Walk Test time and smoothness parameters in Condition 2 (p < 0.05). Comparison between walking conditions within each group showed significant differences in the Figure-of-Eight Walk Test parameters in the two novel conditions in comparison with the original Figure-of-Eight Walk Test. The Figure-of-Eight Walk Test and the novel conditions demonstrated excellent internal consistency, good convergent construct validity, and evidence of known-groups construct validity. Future studies should further develop and standardise the smoothness scale to better quantify walking performance and assess the responsiveness and reliability (inter-rater and intra-rater) of the Figure-of-Eight Walk Test (time and steps) and the novel conditions, while studies on known-groups validity should include persons with a wider mobility range.IMPLICATIONS FOR REHABILITATIONFigure-of-Eight Walk Test with the two novel conditions, which include carrying a load and walking on uneven terrain, may help to provide meaningful information about walking ability in daily life.The two novel conditions pose different challenges to persons with lower limb amputation when compared to the original Figure-of-Eight Walk Test and underscore the relevance to assess mobility under challenging walking conditions.The Figure-of-Eight Walk Test and the two novel conditions demonstrated excellent internal consistency, good convergent construct validity, and evidence of known-groups construct validity.

Acute Post-Exercise Blood Pressure Responses in Middle-Aged Persons with Elevated Blood Pressure/Stage 1 Hypertension following Moderate and High-Intensity Isoenergetic Endurance Exercise.

This study investigated the acute post-exercise hypotension (PEH) response in persons with elevated blood pressure or stage 1 hypertension following moderate and high-intensity isoenergetic endurance exercise. Twelve middle-aged persons (six females), with resting systolic and diastolic BP of 130±6 and 84±7 mmHg, participated in three bicycle ergometer bouts: 1) Testing of peak aerobic capacity (VO2peak), 2) Moderate intensity exercise (MOD) at 66% of VO2peak, 3) High-intensity exercise (INT) at 80% of VO2peak. All variables were recorded pre-exercise, during exercise and 0, 5, 10, and 30 minutes post-exercise. The total duration of exercise was 26% longer during MOD than INT (p <0.001), while total energy expenditure (TEE) was similar between exercise conditions (359 ± 69 kcal). Oxygen consumption, heart rate, power output and ratings of perceived exertion was 21, 13, 21 and 26% higher during INT than MOD exercise, respectively (0.05 ≤ p ≤ 0.001). Compared to pre-exercise, systolic BP was significantly lower at 30 min post-exercise following both INT (p < 0.05) and MOD (p < 0.01) exercise, and there was no difference between INT and MOD conditions. Other variables were similar to pre-exercise values at 30 min post-exercise. Linear regression shows that the largest post-exercise reductions in systolic BP was found for the persons with the highest pre-exercise systolic BP (r = 0.58 r2 = 0.33, p < 0.003). In conclusion, this study shows that endurance exercise with different intensities and durations, but similar TEE is equally effective in eliciting reductions in the post-exercise systolic BP. Furthermore, the magnitude of PEH response is partly dependent on the individuals' resting blood pressure.

Effects of knee orthoses on kinesthetic awareness and balance in healthy individuals.

INTRODUCTION: Conflicting evidence exists regarding the effects of knee orthoses on proprioception. One belief is that pressure applied by orthoses heightens kinesthetic awareness and that this affects balance. This study aimed to investigate the effects of two different orthosis designs on kinesthetic awareness and balance in healthy individuals. METHODS: Twenty individuals (13 women) participated in this case series study. Each was tested wearing 1/no orthosis, 2/soft elastic orthosis and 3/non-elastic jointed orthosis. Pressure under orthoses was recorded. Kinesthetic awareness was investigated by testing joint position sense and threshold to detection of passive motion. Balance was tested using a modified sensory organization test. RESULTS: Non-elastic jointed orthoses applied the greatest pressure to the knee. With non-elastic jointed orthoses, threshold to detection of passive motion was significantly poorer for pooled results (p = 0.02) and when the start position of the knee was 70° (mean threshold = 0.6°, 0.6°, 0.7° for no-orthosis, elastic and jointed-orthoses; p = 0.03). No major differences were observed in JPS or balance and correlation between proprioception and balance was poor. CONCLUSIONS: There may be a limit to the amount of pressure that should be applied to the knee joint by an orthosis. Exceeding this limit may compromise kinesthetic awareness.

Carbohydrate and fat oxidation in persons with lower limb amputation during walking with different speeds.

BACKGROUND: Studies suggest that the energy expenditure of healthy persons (control) during walking with the preferred walking speed in steady-state conditions is dominated by fat oxidation. Conversely, carbohydrate and fat oxidation during walking is little investigated in transfemoral amputees. OBJECTIVES: To investigate carbohydrate and fat oxidation, energy cost of walking, and percent utilization of maximal aerobic capacity [Formula: see text]during walking. STUDY DESIGN: Eight transfemoral amputees and controls walked with their preferred walking speed and speeds 12.5% and 25% slower and faster than their preferred walking speed. METHODS: Energy expenditure and fuel utilization were measured using a portable metabolic analyzer. Metabolic values are means ± standard deviation. RESULTS: For transfemoral amputees (37.0 ± 10.9 years) and controls (39.0 ± 12.3 years), fat utilization at the preferred walking speed was 44.8% ± 7.2% and 45.0% ± 7.2% of the total energy expenditure, respectively. The preferred walking speed of the transfemoral amputees and controls was close to a metabolic cross-over speed, which is the speed where carbohydrate utilization increases steeply and fat utilization decreases. When walking fast, at 90 m min-1 (preferred walking speed plus 25%), transfemoral amputees utilized 70.7% ± 5.6% of their [Formula: see text], while the controls utilized 30.9% ± 4.5% ( p < 0.001) at the matching speed (control preferred walking speed). At 90 m min-1, carbohydrate utilization was 78% ± 4.7% and 55.2% ± 7.2% of the total energy expenditure for the transfemoral amputees and controls, respectively ( p < 0.01). Compared to the control, energy cost of walking was higher for the transfemoral amputees at all speeds (all comparisons; p < 0.001). CONCLUSION: At the preferred walking speed, carbohydrate, not fat, dominates energy expenditure of both transfemoral amputees and controls. For the transfemoral amputees, consequences of fast walking are very high [Formula: see text] utilization and rate of carbohydrate oxidation. Clinical relevance Research on the relationships between physical effort and fuel partitioning during ambulation could provide important insights for exercise-rehabilitation programs for lower limb amputees (LLA). Regular endurance exercise will improve maximal aerobic capacity and enable LLA to walk faster and at the same time expend less energy and improve fat utilization.

Skeletal muscle metabolism after stroke: A comparative study using treadmill and overground walking test.

OBJECTIVE: The primary aim of this study was to investigate muscle metabolism in stroke survivors through measurements of the respiratory exchange ratio and rates of fat and carbohydrate oxidation in relation to total energy expenditure at preferred walking speed during treadmill and overground walking. The secondary objective was to investigate whether the energy source used during walking influences the daily physical activity pattern and fatigue of post-stroke individuals. METHODS: The sample comprised 28 stroke participants and 10 non-disabled, healthy controls. Measurements of oxygen consumption and carbon dioxide production were recorded. Participants wore a uniaxial accelerometer (activPAL™) over 4 days as an estimate of daily physical activity. Measurements of Human Activity Profile and Neurological Fatigue Index for stroke were documented. RESULTS: Carbohydrate oxidation accounted for the majority of fuel oxidation at preferred walking speed in the stroke group (55.86% vs 47.29% during tread-mill walking and 66.13% vs 50.15% during overground walking). Stroke patients who had higher levels of carbohydrate oxidation reached a lower score in the Human Activity Profile survey, had fewer steps screened by activPAL data (4,422 vs 6,692 steps/day) and higher fatigue index. CONCLUSION: Carbohydrate oxidation accounted for the majority of fuel oxidation at the preferred walking speed in post-stroke individuals. The increased carbohydrate utilization recorded at preferred walking speed may have influenced the physical activity profile.

Acute hemodynamic and cardiovascular responses following resistance exercise to voluntary exhaustion. Effects of different loadings and exercise durations.

BACKGROUND: The aim of this study was to compare the acute hemodynamic and cardiovascular responses of high load/low repetition resistance training (RT) to low load/high repetition RT. METHODS: Thirteen healthy men performed four sets of 4 repetition maximum (RM) and 20RM leg-extensions without breath-holding. The RT was conducted in a randomized order and with 48 hours between bouts. Non-invasive beat-to-beat systolic and diastolic blood-pressure (SBP/DBP) was measured on the finger, while non-invasive cardiac output (CO) was assessed beat-to-beat by impedance-cardiography. RESULTS: Mean±SD resting SBP/DBP and CO were 126±14/73±9 mmHg and 5.6±9 L min-1, respectively. Exercise SBP/DBP values increased to 154±22/99 ±18 and 203±33/126±19 mmHg following 4RM and 20RM RT, respectively (compared to rest, all; P<0.001), and 20RM SBP/DBP values were higher than 4RM values (both, P<0.001). The SBP increased from the first to the fourth set of exercise following the 20RM load (P<0.01), but not so for the 4RM load. Exercise SBP/DBP values following the 4th rep of 20RM exercise (154±18/91±14), was similar to the 4RM values, but different to the 20th rep of the 20 RM loading (both; P<0.001). CO increased to 10.8±2.6 and 13.9±2.2 L min-1, following 4RM and 20RM RT, respectively (compared to rest, both; P<0.001) and 20RM CO was higher than 4RM CO (P<0.01). CONCLUSIONS: 20RM RT resulted in higher blood-pressure than 4RM RT when performed to voluntary exhaustion. Differences in hemodynamic responses seems to be related to training duration and not to difference in loading.

Energy expenditure of transfemoral amputees during floor and treadmill walking with different speeds.

BACKGROUND: Walking energy expenditure, calculated as the percent utilization of the maximal aerobic capacity, is little investigated in transfemoral amputees. OBJECTIVES: Compare the energy expenditure of healthy participants (control participants) and transfemoral amputees walking with their respective preferred walking speeds on the treadmill (TPWS) and floor (FPWS). STUDY DESIGN: Randomized cross-over study. METHODS: Oxygen uptake (VO2) was measured when walking with the FPWS and TPWS. VO2max was measured by an incremental treadmill test. RESULTS: Mean ± standard deviation VO2max of the transfemoral amputees and control participants were 30.6 ± 8.7 and 49.0 ± 14.4 mL kg(-1) min(-1), respectively (p < 0.05). TPWS for the transfemoral amputees and control participants was 0.89 ± 0.2 and 1.33 ± 0.3 m s(-1), respectively (p < 0.01). FPWS for the transfemoral amputees and control participants was 1.22 ± 0.2 and 1.52 ± 0.1 m s(-1), respectively (p < 0.01). Walking on floor with the FPWS, the energy expenditure of the transfemoral amputees and control participants was 54% and 31% of VO2max, respectively (p < 0.01). Walking on the treadmill with the TPWS, the energy expenditure of the transfemoral amputees and control participants was 42% and 29% of the VO2max, respectively (p < 0.05). CONCLUSION: Energy expenditure is higher for the transfemoral amputees than the control participants, regardless of walking surface. There are minimal differences in energy expenditure between treadmill and floor walking for the control participants but large differences for the transfemoral amputees. CLINICAL RELEVANCE: During walking, the transfemoral amputees expend a larger percentage of their maximal aerobic capacity than healthy participants. With a low VO2max, ordinary activities, such as walking, become physically more challenging for the transfemoral amputees than the control participants, and this may, in turn, have a negative effect on the walking range of the transfemoral amputees.

Near-Infrared Spectra in Buccal Tissue as a Marker for Detection of Hypoxia.

INTRODUCTION: Hypoxia caused by high altitude exposure can impair cerebral and mental functions. Blood flow and oxygenation of the buccal tissue can be reliable markers to detect hypoxia. In this study, near infrared spectroscopy was used in combination with a novel optical probe to evaluate the applicability of the novel probe in measuring hypoxia markers in buccal tissue under a hypoxic condition. METHODS: Six healthy participants were tested at altitudes from 2000 to 16,000 ft inside a hypobaric chamber. The buccal reference measurements of blood flow and oxygen saturation were synchronized with the spectral measurements of the novel near infrared probe and the relationship between the reference measurements and spectral data were evaluated by multivariate partial least square method. In addition, finger oxygen saturation was measured during the experiment and the recordings were compared with buccal oxygen saturation. RESULTS: The spectral analysis illustrated that the spectral data from the near infrared probe correlated strongly with the absorption features of both buccal flow and oxygenation measured by the reflectance sensors (average R(2) = 0.89). The results showed probably overestimated values for buccal oxygen saturation recorded by the reference pulse oximeter in comparison with finger oxygen saturation, with the mean difference increasing from 1.8% at 2000 ft to 11.4% at 16,000 ft. CONCLUSION: The novel near infrared probe showed promising results for simultaneous measurement of blood flow and oxygen saturation in the buccal tissue. The suggested method can be used as a new technique for early indication of hypoxia in future clinical applications.