One minute of stair climbing and descending reduces postprandial insulin and glucose with 3-min improving insulin resistance following a mixed meal in young adults: A Randomized Controlled Crossover Trial.

Background: Glycemic markers, including postprandial glucose, insulin, and insulin resistance, are strong predictors of morbidity and mortality in individuals with and without diabetes. Stair-climbing and -descending (SCD) at a comfortable pace for 3 minutes after a sugary beverage (300 kilocalories; 100% carbohydrate) lowers insulin, with insulin sensitivity improving in 10 minutes. If similar benefits are seen following consumption of a mixed meal is unknown. We hypothesize SCD will improve these markers in a dose-response manner following a mixed meal. Methods: In a randomized, controlled, crossover trial, young adults (N = 31) performed SCD for 0 (seated control), 1, 3, and 10 minutes after a mixed meal (650 kilocalories; 53% carbohydrates, 33% fat, and 14% protein). Differences in glucose, insulin, and insulin sensitivity (ISI) from baseline to 30 min were analyzed using a mixed-effects ANOVA. Results: A significant fixed-effect was found for change in glucose [F(2.551,67.17) = 4.724,p = 0.007)], insulin [F(2.692,74.49) = 11.28,p < 0.001)], and ISI [F(2.127,56.00) = 5.848,p = 0.004)]. Compared to the seated control (0 minutes), changes in glucose were lower after 1 minute (-14.0 (-7.2)mg/dL,p < 0.001), 3 minutes (-18.4 (-7.0)mg/dL,p = 0.0007), and 10 minutes (-10.0 (-8.1)mg/dL,p = 0.039); changes in insulin were lower after 1 minute (-1.8 (-0.9)µIU/mL,p = 0.0011), 3 minutes (-2.8 (-0.9)µIU/mL,p < 0.001), and 10 minutes (-1.1 (-0.9)µIU/mL,p = 0.033); and changes in ISI were significantly higher after 3 minutes (2.4 (1.5),p < 0.001) and 10 minutes (1.3 (1.6),p = 0.014) but not 1 minute (1.2 (1.5),p = 0.059). Conclusion: Postprandial glucose and insulin improved with 1 minute, and insulin resistance improved with 3 minutes, of SCD at a self-selected, comfortable pace, after consumption of a mixed meal in apparently healthy young adults. Protocol: Trial registration: ClinicalTrials.gov Identifier: NCT04232475.

Salsalate Improves Postprandial Glycemic and Some Lipid Responses in Persons With Tetraplegia: A Randomized Clinical Pilot Trial With Crossover Design.

Objectives: To investigate the effects of salsalate on fasting and postprandial (PP) glycemic, lipidemic, and inflammatory responses in persons with tetraplegia. Methods: This study was a randomized, double-blind, cross-over design. It was conducted at a university laboratory. Ten males aged 25 to 50 years with SCI at C5-8 levels for ≥1 year underwent 1 month of placebo and salsalate (4 g/day) treatment. Blood samples were drawn before and 4 hours after breakfast and lunch fast-food meal consumption. Results: Descriptive statistics indicate that fasting and PP glucose values were reduced with salsalate (pre-post mean difference, 4 ± 5 mg/dL and 8 ± 8 mg/dL, respectively) but largely unchanged with placebo (0 ± 6 mg/dL and -0 ± 7 mg/dL, respectively). Insulin responses were generally reciprocal to glucose, however less pronounced. Fasting free fatty acids were significantly reduced with salsalate (191 ± 216 mg/dL, p = .021) but not placebo (-46 ± 116 mg/dL, p = .878). Results for triglycerides were similar (25 ± 34 mg/dL, p =.045, and 7 ± 29 mg/dL, p = .464). Fasting low-density lipoprotein (LDL) levels were higher after salsalate (-10 ± 12 mg/dL, p = .025) but not placebo (2 ± 9 mg/dL, p = .403) treatment. Inflammatory markers were largely unchanged. Conclusion: In this pilot trial, descriptive values indicate that salsalate decreased fasting and PP glucose response to fast-food meal challenge at regular intervals in persons with tetraplegia. Positive effects were also seen for some lipid but not for inflammatory response markers. Given the relatively "healthy" metabolic profiles of the participants, it is possible that salsalate's effects may be greater and more consistent in people with less favorable metabolic milieus.

Type 1 diabetes mellitus diagnosis in young adult preceded by years of elevated postprandial and fasting glucose but normal HbA1c: A clinical example of discordance.

Herein, a case study of an individual with fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), and postprandial blood glucose (PBG) measures from the 3 years preceding their type 1 diabetes mellitus diagnosis is used to highlight discordance among these common diagnostic tests. Data from the patient's own records, participation in clinical research, and healthcare provider were collated. Measures of FBG (90-160 mg/dL) and PBG (195-247 mg/dL) were elevated for 3 years with a normal HbA1c (5.0-5.4%) and without any symptoms. Overt symptoms, including polyuria, polydipsia, and unexplained weight loss, manifested 3 years later prompting the patient to contact their physician. Testing revealed an elevated HbA1c (9.8%) and presence of glutamic acid decarboxylase autoantibodies (GAD) (9 IU/mL). Daily body composition measures and weighed food logs from the 3 months preceding and 4 months after diagnosis illustrate the effects of glucose spilling and inadequate insulin levels. Both FBG and PBG indicated diabetes 3 years prior to HbA1c. While FBG, PBG, and HbA1c are considered equally appropriate for screening and diagnosing diabetes, this case study highlights the need to revisit important distinctions between these tests that explain their frequent discordance.

Sex differences in the acute effect of stair-climbing on postprandial blood glucose levels: A randomized controlled trial.

Single, short stair climbing and descending (SCD) bouts of low to moderate intensity effectively lower postprandial blood glucose but previous reports have found conflicting results on interactions by sex during exercise. We hypothesize that SCD at a self-selected intensity will be equally effective at lowering postprandial blood glucose in males and females. Methods and Results: Thirty subjects (age: 23.8 (3.0) years) performed 0, 1, 3, and 10 min of SCD following consumption of a mixed meal. SCD was performed at a self-selected comfortable pace and all bouts ended at minute 28. Postprandial blood glucose was measured every 15 min for 1 h and analyzed as glucose over time, area under the curve (AUC), and incremental AUC (iAUC) using mixed-design ANOVAs with repeated measures. Although there was no interaction between sex and condition or time (p = .129 to .541) for glucose over time, AUC, or iAUC, there was a main effect for sex for glucose over time (p = .004) and AUC (p = .006), but not iAUC (p = .125). Females had higher blood glucose throughout each trial (22% (13 to 31%), p = .004) but both males' and females' postprandial blood glucose was lowered following 10 min of SCD relative to the seated control condition. Conclusions: Males and females benefited equally from single, short SCD bouts of low to moderate intensity despite females having higher blood glucose at all time points. Previous findings of sex differences in the attenuating effect of exercise on postprandial blood glucose are likely due to the use of absolute workloads leading to varying relative intensities.

Three minutes of moderate-intensity stair walking improves glucose and insulin but not insulin sensitivity or total antioxidant capacity.

BACKGROUND AND AIMS: This study examined the effect of moderate intensity stair stepping exercise on the glycemic response, and antioxidant capacity (TAC) during an oral glucose tolerance test (OGTT). METHODS AND RESULTS: Thirty participants (women = 12) completed 4 OGTTs during rest or stair walking bouts of 1, 3, and 10 min in a randomized order. Blood was collected at baseline and 30 min during the OGTTs and analyzed for glucose, insulin, TAC, and lactate. Glucose concentrations were decreased following the 10 min (-22.69 (-34.66 to -10.72) mg/dL, p < 0.002) and 3 min (-15.37 (-25.05 to -5.69) mg/dL, p < 0.004) bouts but not the 1 min bout (-6.18 (-19.54 to 7.18) mg/dL, p = 0.352). Insulin concentrations were decreased following the 10 min (-6.11 (-8.86 to -3.36 µIU/dL), p < 0.001) and 3 min (-2.589 (-4.54 to -0.63) µIU/dL, p < 0.012) bouts but not the 1 min bout (-0.37 (-1.87 to 1.13) µIU/dL, p = 0.616). Insulin sensitivity index values showed a significant increase in the 10-min trial (1.81 (0.03-3.58), p < 0.048), but not during the 3 min (0.65 (-0.66 to 1.96) p = 0.317) or 1 min trial (0.13 (-1.58 to 1.84) p = 0.878). There was no omnibus effect for trial in TAC (p = 0.132, η2 = 0.07). There was no interaction between trial and time for blood lactate (p = 0.621, η2 = 0.02). CONCLUSION: This study provides evidence bouts as short as 3 min decrease postprandial blood glucose and insulin levels but longer bouts are needed to affect insulin sensitivity.

Substrate metabolism during recovery from circuit resistance exercise in persons with spinal cord injury.

INTRODUCTION: Whole body energy expenditure and lipid oxidation (Lox) are upregulated during and after exercise. Persons with spinal cord injury (SCI) generally have a blunted ability to utilize fat during exercise, but it is unknown if their substrate partitioning is affected during recovery from exercise. PURPOSE: To determine the effect of a single session of upper body circuit resistance exercise (CRE) on energy expenditure and Lox during exercise recovery in persons with and without SCI. METHODS: Twenty four persons (3 groups; 7 male and 1 female per group) without paralysis (neurologically intact; N) or with chronic (≥ 1 yr) paraplegia (P) or tetraplegia (T) participated. Energy expenditure and substrate partitioning were assessed via indirect calorimetry before, during, and three times after (up to 120 min after) a single session of CRE, or time-matched seated control (CON). RESULTS: During CRE, all groups experienced a similar relative increase in oxygen consumption (49 ± 13, 55 ± 11, and 48 ± 15% VO2peak for N, P, and T, respectively). The Post0-120 energy expenditure was greater following CRE vs. CON (P < 0.01) and independent of injury characteristics (10.6, 22.6, and 14.3% higher than CON for N, P, and T; P = 0.21). The absolute increase in Lox above CON during recovery was similar for N, P, and T (5.74 ± 2.81, 6.62 ± 3.10, and 4.50 ± 3.91 g, respectively; P = 0.45). CONCLUSIONS: Energy expenditure and lipid utilization was increased similarly following circuit exercise in persons without and with spinal cord injury in a manner independent of level of injury.

Effects of chronic decaffeinated green tea extract supplementation on lipolysis and substrate utilization during upper body exercise.

BACKGROUND: Decaffeinated green tea extract (dGTE) can increase fat oxidation during leg exercise, but dGTE is unsuitable for many people (e.g., those with injuries/disabilities), and its effects on arm exercise and women are unknown. METHODS: Eight adults (23-37 years old, 4 women) performed an incremental arm cycle test to measure peak oxygen uptake (VO2peak), followed by four 1-h trials at 50% VO2peak. Subjects were randomly assigned to 650 mg of dGTE or placebo (PLA) for 4 weeks followed by a 4-week washout and crossover trial. Blood samples were obtained pre-exercise and post-exercise for glycerol and free fatty acid analysis. Respiratory gases were collected continuously. RESULTS: VO2 showed no differences across trials ((0.83-0.89) ± (0.19-0.25) L/min, p = 0.460), neither did energy expenditure ((264-266) ± (59-77) kcal, p = 0.420) nor fat oxidation (dGTE = 0.11 to 0.12 g/min vs. PLA = 0.10 to 0.09 g/min, p = 0.220). Fat oxidation as percentage of energy expenditure was not different for dGTE vs. PLA (23% ± 12% to 25% ± 11% vs. 23% ± 10% to 21% ± 9%, p = 0.532). Glycerol concentration increased post-exercise in all trials, independent of treatments (pre = (3.4-5.1) ± (0.6-2.6) mg/dL vs. post = (7.9-9.8) ± (2.6-3.7) mg/dL, p = 0.867, η2 = 0.005 for interaction), as did free fatty acid ((3.5-4.8) ± (1.4-2.2) mg/dL vs. (7.2-9.1) ± (2.6-4.5) mg/dL, p = 0.981, η2 = 0.000). CONCLUSION: Chronic dGTE supplementation had no effect on lipolysis and fat oxidation during arm cycle exercise in men and women.

Accuracy of Apple Watch fitness tracker for wheelchair use varies according to movement frequency and task.

OBJECTIVES: Individuals with disabilities have high prevalence of sedentary lifestyle, obesity, and cardiometabolic disease. Physical activity monitors (i.e., step counters) are ill-suited for tracking wheelchair pushes. The study purpose was to investigate the validity of a consumer-level fitness tracker (Apple Watch) designed for wheelchair users. METHODS: Validation study. A total of 15 wheelchair users with disabilities and 15 able-bodied individuals completed 3-min bouts of wheelchair propulsion on a treadmill and arm ergometry at pre-determined cadences as well as overground obstacle and Figure 8 courses. Tracker stroke counts were compared against direct observation. RESULTS: We found no interaction of tracker counts and ability status across all tasks (P≥0.550), so results are presented for the combined sample. For treadmill tasks, Bland-Altman analysis (bias±limits of agreement) showed good agreement for only higher-rate fixed-frequency tasks (-15±48, -1±14, 0±5, and 0±27 for low, moderate, high, and variable cadence, respectively). Mean absolute percentage error (MAPE) was 22%, 3%, 1%, and 6%, respectively. Intraclass correlation coefficients (ICCs) (95% confidence intervals) were -0.18 (-0.51-0.20), 0.47 (0.13-0.71), 0.98 (0.96-0.99), and 0.22 (-0.16-0.54). We found significant overestimation by the tracker at low frequency (P<0.01). Arm ergometry showed good agreement across all cadences (0±5, -1±3, 0±8, 6±6). MAPE was 1%, 1%, 1%, and 4%. ICCs were 0.88 (0.77-0.94), 0.95 (0.89-0.97), 0.88 (0.76-0.94), and 0.97 (0.87-0.97). We found minimal (2rpm) but significant differences at variable cadence (P<0.01). Overground tasks showed poor agreement for casual-pace and fast-pace obstacle course and Figure 8 task (-5±18, 0±23, and -18±32, respectively). MAPE was 15%, 18%, 21% and ICCs were 0.90 (0.79-0.95), 0.79 (0.59-0.90), and 0.82 (0.64-0.91). Significant differences were found for propulsion at casual pace (P<0.01) and the Figure 8 task (P<0.01). CONCLUSIONS: Apple Watch is suitable for tracking high-frequency standardized (i.e., treadmill) pushing and arm ergometry but not low-frequency pushing or overground tasks.

A single one-minute, comfortable paced, stair-climbing bout reduces postprandial glucose following a mixed meal.

BACKGROUND AND AIMS: Postprandial blood glucose (PBG) is an independent predictor of disease and mortality risk. To date, the shortest, single, moderate-intensity exercise intervention to reduce PBG is a 1 min bout of stair stepping during an oral glucose tolerance test. Whether this effect translates to real meal consumption is unknown. METHODS AND RESULTS: Subjects (N = 30) participated in a randomized controlled crossover trial performing 0 min (seated control), 1 min, 3 min or 10 min of stair climbing and descending bouts (SCD) at a self-selected pace after consumption of a mixed meal on four separate visits. Compared to control, all SCD reduced PBG at least one timepoint: at 30-min the 3 min (-10.8 (-18.7 to -2.8) mg/dL, p = 0.010) and 10 min (-36.3 (-46.4 to -26.3) mg/dL), p < .001), and at 45-min the 1 min (-7.3 (-13.9 to -0.7) mg/dL, p = 0.030, 3 min (-8.7 (-13.9 to -3.6) mg/dL, p = 0.002 and 10 min SCD (-12.2 (-18.2 to -6.1)mg/dL, p < 0.000) reduced PBG. The area under the curve (AUC) for PBG was lower following the 3 min (-4.4% (-7.5 to -1.4%), p = 0.006) and 10 min (-8.9% (-12.4 to -5.3%), p < 0.001), while the incremental AUC (iAUC) was reduced only following the 10 min (-38.0% (-63.7 to -12.3%), p = 0.005) SCD. All SCD were rated by subjects as very light to light intensity. CONCLUSIONS: Single, subjectively "light" intensity stair climbing and descending bouts as short as 1 min in duration attenuate the postprandial glucose response in normal weight individuals following consumption of a mixed meal. More pronounced effects require longer bouts in a dose-dependent manner.

Validity of Caloric Expenditure Measured from a Wheelchair User Smartwatch.

The objective of this study was to investigate the validity of measured caloric expenditure from a fitness smartwatch designed to measured values in wheelchair users against criterion values from a portable metabolic system. 15 wheelchair users and 15 able-bodied participants completed multiple tasks; wheelchair treadmill routine at 30, 45, and 60 strokes per minute, arm cycle ergometry at 45, 60, and 80 revolutions per minute, and arm cycle ergometry VO2Peak test. There were no interactions for device or task and group (wheelchair users vs. able bodied, p=0.375-0.944) therefore results were pooled across groups for all measures. The smartwatch exhibited poor to moderate caloric expenditure association during wheelchair treadmill routine (ICC<0.39) and arm cycle ergometry (ICC<0.541). Smartwatch underestimated caloric expenditure during the wheelchair treadmill task (Mean differences (Limits of Agreement)) (-2.11 (-8.19-3.96), -3.68 (-12.64-5.28), and -4.51 (-15.05-6.02)) and overestimated during the arm cycle ergometry task (0.89 (-3.10-4.88), 3.40 (-0.31-7.12), and 2.81 (-1.71-7.32)). The smartwatch is currently not well suited to calculate caloric expenditure when performing exercise tasks on a wheelchair treadmill and arm cycle ergometry.

Hand heating lowers postprandial blood glucose concentrations: A double-blind randomized controlled crossover trial.

OBJECTIVES: Examine effect of single hand heating with and without negative pressure on fasting blood glucose (FBG) and postprandial blood glucose (PBG). DESIGN: Double-blind randomized controlled trial with crossover design. SUBJECTS: FBG experiment: 17 healthy subjects (4 males). PBG experiment: 13 healthy subjects (1 males). INTERVENTIONS: Devices included one providing heat only, one heat and negative pressure, and one acting as a sham. For the FBG experiment the devices were used for 30 min. For the PBG experiment the devices were used for one hour during an oral glucose tolerance test (OGTT). OUTCOME MEASURES: Blood glucose measurements were used to determine change in FBG, peak PBG, area under the curve (AUC), and incremental AUC (iAUC). RESULTS: Temperature: Change in tympanic temperature was ≤ 0.15 °C for all trials. FBG: There was no effect on FBG. PBG: Compared to the sham device the heat plus vacuum and heat only device lowered peak blood glucose by 16(31)mg/dL, p = 0.092 and 18(28)mg/dL, p = 0.039, respectively. AUC and iAUC: Compared to the sham device, the heat plus vacuum device and heat only device lowered the AUC by 5.1(15.0)%, p = 0.234 and 7.9(11.1)%, p = 0.024 respectively and iAUC by 17.2(43.4)%, p = 0.178 and 20.5(34.5)%, p = 0.054, respectively. CONCLUSIONS: Heating a single hand lowers postprandial blood glucose in healthy subjects.

Postprandial glucose response moderation by cardiorespiratory fitness following short exercise bouts.

BACKGROUND: Previous reports indicate that postprandial glucose (PPG) responses to exercise may depend on cardiorespiratory fitness (CRF), such that less fit individuals have greater reductions in PPG with exercise. Our aim was to investigate moderating effects of CRF on PPG response following exercise of progressively shorter durations and sedentary rest. METHODS: Thirty-four participants (14 female) completed a 75-g oral glucose tolerance test (OGTT) at seated rest. On three subsequent visits, participants completed additional OGTT with either 1, 3, or 10 minutes of stair-climbing. Fingerstick blood glucose measurements were taken every 15 minutes for 1 hour. CRF was determined using a treadmill ramp test. RESULTS: There was a main effect of condition F(3, 93)=13.07, P<0.001, ηp2=0.30. Stair-climbing reduced PPG iAUC compared to control by -3±27% (P=0.546), -11±29% (P=0.091), and -28±22% (P<0.000) for the 1, 3 and 10 min bouts, respectively. There was no trial by CRF interaction for glucose iAUC F(2.4, 73.8)=0.69, P=0.532, ηp2=0.02. Linear mixed model regression analysis revealed that CRF was not significantly associated with glucose iAUC, b=-14 (-45, 16), P=0.339. CONCLUSIONS: Contrary to previous reports CRF did not moderate PPG responses for either sedentary or exercise conditions in healthy men and women. Short, single-bout stair stepping exercise at a self-selected pace is equally efficient for all fitness levels.

Effect of acute watermelon juice supplementation on post-submaximal exercise heart rate recovery, blood lactate, blood pressure, blood glucose and muscle soreness in healthy non-athletic men and women.

The objective of this study was to determine the effects of a single pre-exercise dose of watermelon juice on submaximal post-exercise heart rate (HR) recovery, blood lactate (BL), blood pressure (BP), blood glucose (BG), and muscle soreness in healthy adults. In a randomised crossover design, 27 healthy non-athletic participants (13 males/14 females) consumed 355 mL of watermelon juice, Gatorade, sugar water, or water. HR and BL were significantly higher post-exercise, and both watermelon juice and sugar water increased postprandial BG. However, there were no significant differences among the supplements in HR recovery, BL, or post-exercise muscle soreness. Watermelon juice prevented increased post-exercise systolic and diastolic BP in females, but not in males. More research is warranted to examine the effect of sex on the efficacy of watermelon consumption for controlling BP.

Cardiometabolic Challenges Provided by Variable Assisted Exoskeletal Versus Overground Walking in Chronic Motor-incomplete Paraplegia: A Case Series.

BACKGROUND AND PURPOSE: People with spinal cord injury (SCI) experience secondary complications including low levels of cardiometabolic activity and associated health risks. It is unknown whether overground bionic ambulation (OBA) enhances cardiometabolic challenge during walking in those with motor-incomplete SCI, thereby providing additional therapeutic benefits. CASE DESCRIPTIONS: One man and one woman with chronic motor-incomplete paraplegia due to SCI. INTERVENTION: Assessment of functional walking capacity with the 10-m and 6-minute walk tests. Participants underwent cardiometabolic measurements including heart rate (HR), oxygen consumption ((Equation is included in full-text article.)O2), energy expenditure (EE), and substrate utilization patterns during OBA and overground walking for 6 minutes each. OUTCOMES: The female participant had low functional walking capacity (walking speed = 0.23 m/s; 6-minute walk = 230 ft). She had higher cardiorespiratory responses during OBA versus overground walking (Δ(Equation is included in full-text article.)O2 = -3.6 mL/kg/min, ΔEE = 12 kcal) despite similar mean HR values (ΔHR = -1 beats per minute). She was able to sustain continuous walking only during the OBA trial. The male participant had greater walking capacity (walking speed = 0.33 m/s, 6 minutes = 386ft) and lower responses during OBA versus overground walking (Δ(Equation is included in full-text article.)O2 = -6.0 mL/kg/min, ΔEE = -18 kcal, ΔHR = -6 beats per minute). He was able to walk continuously in both conditions. DISCUSSION: The participant with lower walking capacity experienced a higher cardiometabolic challenge and was able to sustain exercise efforts for longer period with OBA versus overground walking. Therefore, OBA presents a superior alternative to overground training for cardiometabolic conditioning and associated health benefits in this participant. For the participant with higher walking capacity, OBA represented a lower challenge and appears to be an inferior cardiometabolic training option to overground walking. The cardiometabolic response to OBA differs depending on functional capacity; OBA warrants study as an approach to cardiometabolic training for individuals with motor-incomplete SCI who have limited lower extremity function.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A259).

Sex differences in postprandial glucose response to short bouts of exercise: A randomized controlled trial.

OBJECTIVES: The objective of this study was to assess sex differences in PPG responses to short stair stepping bouts, and to describe their intensity and metabolic cost. DESIGN: Crossover trial. METHODS: 34 participants (age: 25.9±5.5y; women=14) underwent 4 oral glucose tolerance tests (OGTT) during rest or with stair-stepping bouts at self-selected, moderate pace for 1, 3, and 10min. Blood was collected every 15min during the OGTTs and assessed for glucose. Participants also underwent maximal aerobic capacity assessment. Expired gases were collected during capacity testing, and each stair-stepping bout. RESULTS: Normalized to body weight there was no significant interaction for sex with stair-stepping trials (p=0.445, ηp2=0.03), or time (p=0.069, ηp2=0.09), or trial by time (p=0.264, ηp2=0.04). Women had higher mean glucose values than men (15(CI=3, 27)%, p=0.015). iAUC also showed no interaction of sex*trial (p=0.059, ηp2=0.09). Women had higher iAUC values (meanΔ=-29(-48, -11)%, p=0.003). There was a main effect for trial with 10min showing the largest reduction from control for women (e.g. AUC -10(-6, -13)%, p<.001) and men (-8(2, 13)%, p=.010). Metabolic cost of the stair stepping bouts showed no interaction of sex*trial (p=0.715, ηp2=0.01) and no difference between sexes (meanΔ=-1.3(-5.9, 3.4)%, p=0.571). Intensity was higher for women for the 3min (60±11 vs. 48±9%VO2max, p=0.003) and 10min (67±8 vs. 54±12%VO2max, p=0.002) bouts. Moreover, both sexes underestimated the true intensity of stepping. CONCLUSIONS: Both sexes had similar responses to short bouts of exercise, which they perceived as less intense than indicated by objective assessment. Stair stepping reduces postprandial glucose response with similar effectiveness for both sexes. ClinicalTrials.gov Identifier: NCT03400774.

Reducing Glycemic Indicators with Moderate Intensity Stepping of Varied, Short Durations in People with Pre-Diabetes.

Investigate the effects of short duration stair climbing/descending at a self-selected pace on post-prandial glucose responses in adults. Thirty participants (10 female) completed 4 oral glucose tolerance tests on separate days. Following glucose consumption, participants underwent seated rest (control) or walked up/down 21 stairs at a self-selected comfortable pace for 10, 3, and 1min in randomized order. Blood glucose was measured by capillary sampling from finger sticks every 15min until values for all trials converged. Area under the curve (AUC) was calculated by trapezoidal rule. In addition, cardiometabolic measurements were taken during stair exercise with a mobile metabolic cart. Results are presented as mean (SD) unless stated otherwise. All stair-climbing trials reduced peak (30min) postprandial blood glucose levels compared to the control [(1 min = 12(31), p = 0.026; 3 min = -15(25), p = 0.003; 10 min = 35(32) mg/dL, p < 0.001]. At 45min, there were significant reductions only for the 3 and 10 min trials [13(29) and 23(31) mg/dL, p = 0.023 and < 0.001 respectively], but not the 1 min trial [6(33) mg/dL, p = 0.317]. There were significant differences in AUC compared to the control only for the 3 and 10min trials [502 (1141) and 866 (1123) mg/dL·min-1, p = 0.023 and < 0.000] but not for the 1min trial [353 (1265) mg/dL·min-1, p = 0.110]. Median (interquartile range) RPEs reported for the 1, 3, and 10min trials were 1.0 (1.5), 2.0(2), and 3.0 (2.0) respectively, while VO2 was n/a, 54(12), and 59(13)% of peak, respectively. Total metabolic cost was 1.4 (0.5), 4.0 (1.0), and 11.9 (2.1) L O2, respectively. A single 1min bout of low-moderate intensity stair stepping can significantly lower peak glucose concentration, with longer bouts being more effective.

Accuracy and precision of consumer-level activity monitors for stroke detection during wheelchair propulsion and arm ergometry.

The purpose of this study was to evaluate whether consumer-level activity trackers can estimate wheelchair strokes and arm ergometer revolutions. Thirty able-bodied participants wore three consumer-level activity trackers (Garmin VivoFit, FitBit Flex, and Jawbone UP24) on the wrist. Participants propelled a wheelchair at fixed frequencies (30, 45 and 60 strokes per minute (spm)) three minutes each and at pre-determined varied frequencies, (30-80 spm) for two minutes. Participants also freely wheeled through an obstacle course. 10 other participants performed arm-ergometry at 40, 60 and 80 revolutions per minute (rpm), for three minutes each. Mean percentage error (MPE(SD)) for 30 spm were ≥46(26)% for all monitors, and declined to 3-6(2-7)% at 60 spm. For the obstacle course, MPE ranged from 12-17(7-13)% for all trackers. For arm-ergometry, MPE was at 1-96(0-37)% with the best measurement for the Fitbit at 60 and 80 rpm, and the Garmin at 80rpm, with MPE = 1(0-1)%. The consumer-level wrist-worn activity trackers we tested have higher accuracy/precision at higher movement frequencies but perform poorly at lower frequencies.

Aging impairs regulation of ryanodine receptors from extensor digitorum longus but not soleus muscles.

INTRODUCTION: Because impaired excitation-contraction coupling and reduced sarcoplasmic reticulum (SR) Ca2+ release may contribute to the age-associated decline in skeletal muscle strength, we investigated the effect of aging on regulation of the skeletal muscle isoform of the ryanodine receptor (RyR1) by physiological channel ligands. METHODS: [3 H]Ryanodine binding to membranes from 8- and 26-month-old Fischer 344 extensor digitorum longus (EDL) and soleus muscles was used to investigate the effects of age on RyR1 modulation by Ca2+ and calmodulin (CaM). RESULTS: Aging reduced maximal Ca2+ -stimulated binding to EDL membranes. In 0.3 µM Ca2+ , age reduced binding and CaM increased binding to EDL membranes. In 300 µM Ca2+ , CaM reduced binding, but the age effect was not significant. Aging did not affect Ca2+ or CaM regulation of soleus RyR1. DISCUSSION: In aged fast-twitch muscle, impaired RyR1 Ca2+ regulation may contribute to lower SR Ca2+ release and reduced muscle function. Muscle Nerve 57: 1022-1025, 2018.

Body System Effects of a Multi-Modal Training Program Targeting Chronic, Motor Complete Thoracic Spinal Cord Injury.

The safety and efficacy of pharmacological and cellular transplantation strategies are currently being evaluated in people with spinal cord injury (SCI). In studies of people with chronic SCIs, it is thought that functional recovery will be best achieved when drug or cell therapies are combined with rehabilitation protocols. However, any functional recovery attributed to the therapy may be confounded by the conditioned state of the body and by training-induced effects on neuroplasticity. For this reason, we sought to investigate the effects of a multi-modal training program on several body systems. The training program included body-weight-supported treadmill training for locomotion, circuit resistance training for upper body conditioning, functional electrical stimulation for activation of sublesional muscles, and wheelchair skills training for overall mobility. Eight participants with chronic, thoracic-level, motor-complete SCI completed the 12-week training program. After 12 weeks, upper extremity muscular strength improved significantly for all participants, and some participants experienced improvements in function, which may be explained by increased strength. Neurological function did not change. Changes in pain and spasticity were highly variable between participants. This is the first demonstration of the effect of this combination of four training modalities. However, balancing participant and study-site burden with capturing meaningful outcome measures is also an important consideration.

Respiratory, cardiovascular and metabolic responses during different modes of overground bionic ambulation in persons with motor-incomplete spinal cord injury: A case series.

OBJECTIVE: To investigate the effects of overground bionic ambulation with variable assistance on cardiorespiratory and metabolic responses in persons with motor-incomplete spinal cord injury. DESIGN: Case series. SUBJECTS: Four participants with chronic, motor-incomplete spinal cord injury. METHODS: Subjects completed a maximal graded exercise test on an arm-ergometer and 3 6-min bouts of overground bionic ambulation using different modes of assistance, i.e. Maximal, Adaptive, Fixed. Cardiorespiratory (oxygen consumption) and metabolic (caloric expenditure and substrate utilization) measures were taken using a mobile metabolic cart at each overground bionic ambulation assistance. RESULTS: Cardiorespiratory responses ranged from low (24% VO2peak) for the least impaired and fittest individual to supramaximal (124% VO2peak) for the participant with the largest impairments and the lowest level of fitness. Different overground bionic ambulation assistive modes elicited small (3-8% VO2peak) differences in cardiorespiratory responses for 3 participants. One participant had a large (28% VO2peak) difference in cardiorespiratory responses to different modes of overground bionic ambulation. Metabolic responses mostly tracked closely with cardiorespiratory responses. Total energy expenditure ranged from 1.39 to 7.17 kcal/min. Fat oxidation ranged from 0.00 to 0.17 g/min across participants and different overground bionic ambulation modes. CONCLUSION: Overground bionic ambulation with variable assistance can substantially increase cardiorespiratory and metabolic responses; however, these responses vary widely across participants and overground bionic ambulation modes.