Stair-climbing Power Research Articles

Minimal power required to ascend a flight of stairs versus actual power measured with body-fixed sensors in adults aged 19-85 years.

A good stair-climbing (SC) ability is crucial for independent living in older adults. A simple formula that estimates the mean power needed to ascend a flight of stairs in a predetermined time (i.e., total ascent duration) is easy to implement in practice, but lacks information on actual power values generated per step. The latter is possible with body-fixed sensors. This study aimed at comparing both methodologies and investigating their sensitivity to detect age-related differences. 318 participants (162 ♀; age 19-85 years) were tested on a 6-step staircase and two methodologies were used to estimate mean SC power: (1) a body-fixed sensor with automated detection of power production per step, and (2) a mathematic equation based on timed ascent duration, body mass and stair height. SC power was 210.4 W lower with formula compared to sensor, lower in women versus men and in older versus young adults (p < 0.001). The difference in SC power between sensor and formula was greater in individuals with better performance (i.e., men and young adults) (p < 0.001), indicating a ceiling effect of the formula in well-functioning and younger individuals. Likewise, ICC's between both methodologies showed poor reliability in people aged <65 years (0.087-0.363) and moderate to good reliability in people aged ≥65 years (0.453-0.780). To conclude, participants with better SC performance are able to largely overshoot the minimal power required to ascend the stairs in a certain duration. This makes the sensor more sensitive to identify early age-related differences compared to the formula.

Older adults' lower-limb muscle power production throughout a full flight of stairs: Reliability and comparison between different stair models.

Lower-limb muscle power should be closely monitored to prevent age-related functional ability declines. Stair-climbing (SC) power is a functionally relevant measurement of lower-limb muscle power. Body-fixed sensors can measure power production throughout the different steps of a flight of stairs to assess different aspects of performance. This study investigated: 1) power production throughout a full flight of stairs; 2) if staircases with less or more steps can provide similar information; and 3) test-retest reliability of SC power. 116 community-dwelling older adults (57 women) ascended three staircases as fast as possible: 12, 6 and 3 steps. Mean vertical power production per step was collected and analyzed using a commercial body-fixed sensor and software. Three phases were found in SC power production: 1) an acceleration phase, i.e., the power produced in step 1 (P1); 2) a phase where the highest performance (Pmax) is reached and; 3) a fatiguing phase with power loss (Ploss; only measurable on 12-step staircase). Mean power (Pmean) over the different steps was also evaluated. P1 did not differ between staircases (all p>0.05), whereas Pmax and Pmean were higher with increasing number of steps (p = 0.073 -p<0.001). P1, Pmax and Pmean were strongly correlated between staircases (r = 0.71-0.95, p<0.05). and showed good to excellent reliability (ICC = 0.66-0.95, p<0.05). Ploss showed poor reliability. To conclude, measurements of SC power production (P1, Pmax and Pmean) with a single sensor on the lower back are reliable across different staircases. A small, transportable, 3-step staircase can be used for measuring power production in clinical practices with no access to regular staircases. However, absolute values are dependent on the number of steps, indicating that measurements to track performance changes over time should always be done using an identical stair model.

THU512 Elevated Insulin Like Growth Factor Binding Protein 2 Levels Are Associated With Muscle Wasting And Increased Insulin Sensitivity In Cancer Patients

Abstract Disclosure: L. Caeiro: None. L.J. Anderson: None. H. Liu: None. K. Krumm: None. J.M. Garcia: None. Cancer-associated weight loss is a complex metabolic syndrome characterized by a loss of skeletal muscle mass and function. Insulin resistance is present in cancer but its role in cancer-related muscle wasting is poorly understood. Recent data from in vitro and animal models show that tumor-derived insulin-like growth factor binding protein (IGFBP)-2 can lead to skeletal muscle wasting and insulin resistance in cancer. We hypothesized that muscle mass and function would be inversely associated with IGFBP-2 levels and insulin resistance in circulation. IGFBP-2, physical function, body composition, insulin and glucose (to calculate HOMA-IR), quality of life (QOL), and cytokines were assessed in male cancer patients with (CWL, n=25) or without (CWS, n=47) weight loss. Physical Function was assessed by hand grip strength (HGS), stair climb power (SCP), and one repetition maximum (1RM) tests of the major muscle groups. Body composition was measured by bioimpedance (BIA) and CT scans and QOL by Karnofsky and ECOG scores. Blood samples were obtained after an overnight fast to measure IGFBP-2, insulin, glucose, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in plasma. CWL had higher plasma IGFBP2 levels (p = 0.01) and lower skeletal muscle index (SMI) (p = 0.03) and body mass index (BMI) (p = 0.007) when compared to CWS, but no differences were found with SCP, HGS, 1RM tests, or with HOMA-IR. IGFBP2 was negatively correlated with SMI (N = 65, R² = -.58, P = &amp;lt;0.001), BMI (N=73, R² = -.54, P = &amp;lt;0.001), CT-derived muscle mass (N = 48, R² = -.56, P = &amp;lt;0.001), BIA fat percent, (N = 25, R² = -.56, P = 0.005), 6 month weight change (N = 73, R² = -.27, P = 0.020), 12 month weight change (N = 73, R² = -.24, P = 0.044), insulin (N = 53, R² = -.48, P = &amp;lt;0.001) ,and HOMA IR (N = 53, R² = -.51, P = &amp;lt;0.001) and positively correlated with IL-6 (N = 72, R² = .33, P = 0.005) and TNF-α (N = 72, R² = .27, P = 0.021) in cancer patients. HOMA-IR was positively correlated with SMI (N = 31, R² = .39, P = 0.029), CT-derived muscle mass (N = 31, R² = .38, P = 0.036), and BIA fat percent (N = 21, R² = .62, P = 0.003). No association was found with IGFBP2 and QOL, SCP, HGS or the other functional parameters with exception of Knee Extension (N = 26, R² = .39, P = 0.049). In conclusion, cancer weight losing patients have increased IGFBP2 levels that were associated with muscle wasting, decreased fat mass, weight loss, and elevated IL-6 and TNF-α. HOMA-IR was negatively correlated with IGFBP2 and positively correlated with muscle mass. We postulate that a decrease in fat mass seen in weight-losing cancer patients leads to an increase in insulin sensitivity. More studies are needed to test this hypothesis and establish the role of IGFBP-2 as a mediator of muscle wasting in cancer. Presentation: Thursday, June 15, 2023

Higher bone remodeling biomarkers are related to a higher muscle function in older adults: Effects of acute exercise

Bone and muscle are closely linked mechanically and biochemically. Bone hormones secreted during bone remodeling might be linked to muscle mass and strength maintenance. Exercise elicits high mechanical strain and is essential for bone health. However, the relationship between commonly used bone turnover markers (BTMs) and muscle function in community dwelling older adults remains unclear. It is also unknown how acute exercise with differing mechanical strain may affect BTMs, and whether baseline muscle function alters BTM responses differently. We tested the hypothesis that BTMs are associated with muscle function, and that acute exercise could change the circulating levels of BTMs. Thirty-five older adults (25 females/10 males, 72.8±6.0years) participated. Baseline assessments included body composition (DXA), handgrip strength and a physical performance test (PPT) (gait speed, timed-up-and-go [TUG], stair ascent/descent). Leg muscle quality (LMQ) and stair climb power (SCP) were calculated. Participants performed (randomized) 30min aerobic (AE) (cycling 70%HRPeak) and resistance (RE) (leg press 70%RM, jumping) exercise. Serum β-isomerized C-terminal telopeptides (β-CTX), procollagen of type I propeptide (P1NP), total osteocalcin (t)OC and ucOC were assessed at baseline and post-exercise. Data were analyzed using linear mixed models and simple regressions, adjusted for sex. At baseline, higher muscle strength (LMQ, handgrip) was related to higher P1NP, higher SCP was related to higher P1NP and β-CTX, and better physical performance (lower PPT) related to higher P1NP and β-CTX (p<0.05). Exercise, regardless of mode, decreased β-CTX and tOC (all p<0.05), while P1NP and ucOC remained unaltered. Higher baseline handgrip strength, SCP and LMQ was associated with lower post-exercise β-CTX responses, and poorer baseline mobility (increased TUG time) was associated with higher post-exercise β-CTX. Independently of exercise mode, acute exercise decreased β-CTX and tOC. Our data suggest that in older adults at baseline, increased BTM levels were linked to better muscle function. Altogether, our data strengthens the evidence for bone-muscle interaction, however, mechanisms behind this specific component of bone-muscle crostalk remain unclear.

Wearable-Based Stair Climb Power Estimation and Activity Classification.

Stair climb power (SCP) is a clinical measure of leg muscular function assessed in-clinic via the Stair Climb Power Test (SCPT). This method is subject to human error and cannot provide continuous remote monitoring. Continuous monitoring using wearable sensors may provide a more comprehensive assessment of lower-limb muscular function. In this work, we propose an algorithm to classify stair climbing periods and estimate SCP from a lower-back worn accelerometer, which strongly agrees with the clinical standard (r = 0.92, p < 0.001; ICC = 0.90, [0.82, 0.94]). Data were collected in-lab from healthy adults (n = 65) performing the four-step SCPT and a walking assessment while instrumented (accelerometer + gyroscope), which allowed us to investigate tradeoffs between sensor modalities. Using two classifiers, we were able to identify periods of stair ascent with >89% accuracy [sensitivity = >0.89, specificity = >0.90] using two ensemble machine learning algorithms, trained on accelerometer signal features. Minimal changes in model performances were observed using the gyroscope alone (±0–6% accuracy) versus the accelerometer model. While we observed a slight increase in accuracy when combining gyroscope and accelerometer (about +3–6% accuracy), this is tolerable to preserve battery life in the at-home environment. This work is impactful as it shows potential for an accelerometer-based at-home assessment of SCP.

Exercise interventions for older people at risk for frailty: A protocol for systematic review and meta-analysis.

Background:Frailty is a state of age-related reduced physiological reserve characterized by an increased risk of adverse clinical outcomes. Studies have shown that exercise can improve frailty in older people. However, it remains to be seen which exercises will most improve the fitness of older people with frailty or those at the risk for frailty.Objective: This protocol aims to determine whether physical exercise can improve frailty in older people, and if which methods are most effective.Methods:We searched the following databases for relevant articles published between January 1, 2012 and January 1, 2021: PubMed, EMBASE, the Cochrane Library, Wanfang, the China National Knowledge Infrastructure, Clinical Trials Database, and the Science Network. Two independent reviewers will carry out data extraction, discuss and resolve differences, and obtain consensus from the third author. We will select randomized control trials (RCTs) according to the preformulated inclusion criteria. The main outcomes in this study are scores from Fried Frailty Phenotype Criteria; the Frailty Trait Scale–short form; the SHARE Frailty Instrument; the FRAIL scale; the Gérontopôle Frailty Screening Tool; the Clinical Frailty Scale, the Rockwood and Mitnitsky Frailty Index; the Study of Osteoporotic Fractures Index; the Edmonton Frailty Scale; the Fatigue, Resistance, Ambulation, Illness and Loss of Weight Index; the Multidimensional Prognostic Index; the Tilburg Frailty Indicator; PRISMA-7; the Groningen Frailty Indicator; the Sherbrooke Postal Questionnaire; and the Kihon Checklist. Secondary outcomes are muscle strength, gait velocity, stair-climbing power, and level of spontaneous physical activity. If the heterogeneity test shows slight or no statistical heterogeneity, a fixed effects model will be used for data synthesis; otherwise, a random effects model will be used. We will develop a unified data extraction table that includes a number of parameters. The Cochrane Cooperative Bias Risk Tool will be used to evaluate the methodological quality of the selected RCTs. RevMan Manager 5.3 and STATA 14.0 will be used for data analysis if enough RCTs (more than 10) are identified and selected.Result:The final results will provide information on the effectiveness of intervention programs for frail older adul and further demonstrate which exercise programs are more effective and which methods can significantly improve frailty.Conclusion:This protocol will contribute to the development of more effective interventions for elderly individuals with frailty.Ethics and dissemination:This study applies existing literature references; therefore, ethical approval is not required.INPLASY registration number:INPLASY202130107

Resistance exercises improve physical function in chronic Chikungunya fever patients: a randomized controlled trial

Chikungunya fever is an arboviral disease, caused by an alphavirus, the Chikungunya virus, characterized by fever and joint pain that is generally disabling in the acute phase and may last from months to years, with the potential to evolve into chronic musculoskeletal symptoms, as polyarthralgia and arthritis, which can lead to significant impairment of physical function. The non-pharmacological treatment is very important for these patients, and resistance exercises may be one rehabilitation option. This study aimed to evaluate the efficacy of a resistance exercise protocol on the physical function, pain, and quality of life of patients with chronic Chikungunya fever. A randomized, controlled, blind trial for the evaluators. Clinic-school of Physical therapy. Thirty-one patients with Chikungunya fever and musculoskeletal symptoms lasting more than three months, recruited from the Rheumatology outpatient clinic at Clinical Hospital, Federal University of Pernambuco (HC-UFPE). Patients (aged 56±10 years) were randomly assigned into one of two groups: Resistance Exercise Group (REG, N.=15) or Control Group (CG, N.=16). REG performed progressive resistance exercises with elastic bands (24 sessions over 12 weeks). CG only had their symptoms monitored through phone calls, maintaining the usual care treatment. Assessments were taken at baseline and after 6 and 12 weeks of the following: physical function (30-second Chair Stand Test (30-s CST), 4-step Stair Climb Power Test (4SCPT), 40-m Fast-paced Walk Test (40m FPWT), and Disabilities of the Arm, Shoulder, Hand (DASH) questionnaire); pain (VAS and painful joints count); quality of life (Medical Outcomes Study 36-Item Short-Form Health Survey [SF-36]); and Patient Global Impression of Change (PGIC) scale. There was a reduction of pain (P=0.01; d=-0.83) and an improvement of 30-s CST (P=0.04; d=0.85) in REG participants after 12 weeks. There was no significant change in the domains of SF-36. Nearly 70% of trained patients reported improvement on PGIC. Resistance exercises improved physical function in sitting and standing and reduced pain in patients with chronic Chikungunya fever. Resistance exercises can be considered as a treatment approach for patients with musculoskeletal disorders in the chronic stage of Chikungunya fever.

Evaluation of physical function and its association with body composition, quality of life and biomarkers in cancer cachexia patients

There are currently no approved treatments for cancer cachexia. One of the main barriers to developing a treatment for this indication is the lack of consensus on clinically important tools for assessing functional impairment in this setting. This issue is of critical importance because functional improvement is likely to be required for approval by regulatory agencies. This cross-sectional study aimed to evaluate various functional performance measures and establish their association with body composition, energy expenditure, biomarkers, and patient-reported quality of life (QOL). Physical function, body composition, energy expenditure, cytokines, testosterone, and patient-reported QOL were compared between men with solid tumors with cachexia (CAC; N=48), without cachexia (CNC; N=48), and weight-stable patients without cancer (CON; N=37). Receiver Operator Characteristic curves and multivariate regression were performed to identify functional impairment cut-points and predictors of physical function, respectively. Patients with CAC displayed lower total lean and appendicular lean mass, stair climb power (SCP), upper body strength, and bioavailable testosterone, and displayed higher energy expenditure than CNC or CON (p≤0.03); CAC showed lower handgrip, respiratory quotient, and appetite, and higher cytokines and fatigue than CON (p≤0.032). A cut-point of 336 Watts for SCP provided 78% sensitivity and 77% specificity for classification of CAC (p=0.001); SCP also performed better than other measures tested when compared to CON-derived normatives. Upper body strength exhibited moderate sensitivity and specificity for classification of CAC (p≤0.02). Elevated relative energy expenditure and cytokines negatively predicted, and muscle mass positively predicted, various muscle strength outcomes. Stair climb power and upper body strength may have potential as discriminatory tests for functional impairment in patients with cancer cachexia.

Reliability Of Muscle Power And Functional Performance In Healthy, Older Women

Functional performance measures in older adults are commonly used in studies investigating age-related declines in mobility. Surprisingly, there is a lack of literature on the clinimetric properties associated with these tests, especially in healthy, older adults. In addition, reliability of tests is commonly measured over 1-2 weeks, and does not address the question of longer-term reliability that might be more relevant for a typical training study. PURPOSE: The purpose of this study was to assess the longer-term reliability (over 9 weeks and 15 weeks) of an isotonic muscle power test (using an isokinetic dynamometer) and commonly-used functional measures (Short Physical Performance Battery, maximal gait, 30s chair stand test, stair climbing, and the 400-meter walk) in healthy, older women. METHODS: Participants were older women (n = 18) who were healthy and untrained (Age = 73.3 ± 3.4 years, Height = 159.6 ± 7.7 cm, Weight = 69.5 ± 12.7 kg, BMI = 27.3 ± 4.8). Test-retest measures (muscle power and function) took place at baseline, week 9, and week 15. Intraclass correlation coefficients (ICC) and the coefficient of variation of the typical error (CV) are reported for all time point comparisons. RESULTS: ICCs ranged from 0.83-0.97 for muscle power, and 0.64-0.93 for functional performance, indicating moderate to excellent reliability. CVs for upper-leg muscle power ranged from 5.7 - 10.5%, and lower-leg muscle power ranged from 9.9 - 20.0%, while CVs for functional tests ranged from 1.9 - 14.9%. For function, the stair-climb power test demonstrated the greatest reliability from baseline to week 15, with the CV = 8.94% and ICC = 0.94 (CI = 0.82-0.98). There were no changes in mean values for tests over time, with the exception of the chair stands which improved significantly from baseline to week 15 (p < 0.05). Although the chair stands were significantly different, these changes were smaller than what has previously been identified as clinically meaningful (eg. < 3.3 chair stands for the 30s chair stand test). CONCLUSIONS: Muscle power and functional tests demonstrated consistency over durations typically used in exercise studies. Conducting these tests under standardized conditions should enable researchers to confidently describe the impact of exercise interventions on muscle power and function in this population.

Muscle mass, not radiodensity, predicts physical function in cancer patients with or without cachexia.

Background: There is a need to better understand the relationship between functional impairment and muscle mass in cancer cachexia. This study aimed to establish the relationship between computed tomography (CT)-derived muscle cross-sectional area (CSA), radiodensity, and skeletal muscle index (SMI) and dual energy X-ray absorptiometry (DXA) parameters with functional performance in cancer patients.Materials and Methods: Handgrip strength, stair climb power (SCP), one-repetition maximum (1RM) strength, and body composition (CT and DXA) were compared across cancer patients with cachexia (CAC; N = 28), without cachexia (CNC; N = 28), and non-cancer patients (CON; N = 19). Multivariate regression was performed to find predictors of function.Results: CAC had lower CT muscle CSA and SMI and lower DXA appendicular lean mass (ALM) than CNC or CON (p ≤ 0.011). Muscle radiodensity was not different across groups despite larger proportion of low CT SMI in CAC, and CAC performed worse in SCP than CON (p = 0.018). In cancer patients, DXA ALM and CT muscle CSA each predicted physical function (p ≤ 0.05); muscle radiodensity did not, and DXA ALM explained more variability in SCP and 1RM than CT muscle CSA.Conclusions: Stair climb power was reduced in cancer cachexia; muscle radiodensity was not. Muscle mass by CT or DXA, but not radiodensity, predicted functional performance in cancer patients.

Moderate Intensity Resistive Training Reduces Oxidative Stress and Improves Muscle Mass and Function in Older Individuals.

An innovative moderate-intensity resistive exercise-training (RT) program was tested in thirty-five sarcopenic elders (SAR). The subjects were randomized into two groups: SAR training (SAR-RT), n = 20, 73.0 ± 5.5 years, or SAR non-training (SAR-NT), n = 15, 71.7 ± 3.4 years. The training consisted of 12-week progressive RT, thrice/week, at 60% one-repetition maximum (1RM), 3 sets, 14–16 repetitions for both upper and lower limbs. The pre and post intervention measurements included: the skeletal muscle index (SMI%); strength (1RM); stair-climbing power (SCP); muscle thickness (MT) of vastus lateralis (VL) and elbow flexors (EF), VL pennation angle (PA), rectus femoris (RF) anatomical cross-sectional area (ACSA); reactive oxygen species (ROS), total antioxidant capacity (TAC), protein carbonyls (PC), thiobarbituric acid-reactive substances (TBARS), 8-isoprostane (8-iso-PGF2-α), 8-OH-2-deoxyguanosine (8-OH-dG), as markers of oxidative stress/damage (OxS). In SAR-RT, SCP increased by 7.7% (P < 0.01), MT increased by 5.5% for VL, 10.4% for EF and PA increased by 13.4% for VL (P < 0.001 for all). The RF ACSA increased by 14.5% (P < 0.001). 1RM significantly increased by at least 67% for all muscles tested. Notably muscle strength (1RM) positively correlated (P < 0.001) with TAC and negatively with PC (P < 0.001). In conclusion, moderate intensity RT is an effective strategy to increase muscle mass and strength in SAR, while minimizing OxS.

The Stair Climb Power Test as an Efficacy Outcome in Randomized Trials of Function Promoting Therapies in Older Men.

Standardization of performance-based physical function measures that are reliable and responsive to intervention is necessary for efficacy trials of function promoting anabolic therapies (FPTs). Herein, we describe a standardized method of measuring stair climbing power (SCP) and evaluate its ability to assess improvements in physical function in response to an FPT (testosterone) compared to gait speed. We used a 12-step SCP test with and without carrying a load (loaded, LSCP or unloaded, USCP) in two testosterone trials in older men. SCP was determined from mass, total step-rise, and time of ascent measured with an electronic timing system. Associations between SCP and leg press performance (strength and power), testosterone levels, and gait speed were assessed. Test-retest reliability was evaluated using interclass correlation and Bland-Altman analyses. Baseline SCP was negatively associated with age and positively with leg strength and power and gait speed. Both tests of SCP were safe and showed excellent reliability (intra-class correlation 0.91-0.97 in both cohorts). Changes in testosterone concentrations were associated with changes in USCP and LSCP, but not gait speed in mobility-limited men. Changes in leg press performance were associated with SCP in both trials. Both USCP and LSCP are safe and have high test-retest reliability. Compared to gait speed, SCP is associated more robustly with leg press performance and is sensitive to testosterone therapy. The LSCP might be a more responsive outcome than gait speed to evaluate the efficacy of FPT in randomized trials.

Functional Performance With Age: The Role of Long-Term Strength Training.

Physical function is shown to decline with age. However, how long-term strength training may attenuate the age-related limitation in functional tasks with various force demands is unclear. In a cross-sectional study, we assessed maximal muscle strength, initial and late phase rate of force development (RFD), as well as 4 tests of functional performance in 11 strength-trained master athletes (MAs), 11 recreationally active older adults (AEs), 10 sedentary older adults (SOAs), and 9 moderately active young controls. Functional performance was divided into 2 categories: more force-demanding (chair-rising ability and stair-climbing power) and less force-demanding (habitual walking speed and 1-leg standing) tasks. MA exhibited 75%, 45%, and 26% higher leg press maximal strength compared with SOA, AE, and young, respectively (P < .01). MA leg press RFD was not different from young, but was higher compared to AE and SOA during both the initial (0-50 ms: 104%-177%, P < .05) and late phase (100-200 ms: 37%-52%, P < .05) of muscle contraction. MA also showed better mean (SD) performance compared with AE and SOA (P < .05) in more force-demanding functional tasks; chair-rising ability (MA: 6.2 (1.2) seconds; AE: 8.6 (1.8) seconds; SOA: 9.7 (3.0) seconds; young: 6.5 (1.0) seconds) and stair-climbing power (MA: 701 (161) W; AE: 556 (104) W; SOA: 495 (116) W; young: 878 (126) W). No differences (mean (SD)) were observed between MA and AE in less force-demanding tasks, but both groups were superior (P < .05) compared with SOA in walking speed (MA: 1.49 (0.21) m·s; AE: 1.56 (0.17) m·s; SOA: 1.27 (0.22) m·s; young: 1.62 (0.22) m·s) and balance test completion (MA: 45%; AE: 45%; SOA: 0%; young: 100%). Our results reveal that maintaining a high muscle force-generating capacity into older age is related to beneficial effects on functional performance, which may not be achieved with recreational activity, thus highlighting strength training as an important contribution to healthy aging.

Identification of T-cell subsets associated with muscle strength in people with cancer: A pilot study

Abstract Background Immune deficiency and muscle wasting are both associated with poor prognosis in people with cancer. Survival and quality of life can be improved by attenuating either the immune response or muscle mass, suggesting a relationship between them. Previous data show that mice injected with precursor CD4 T cells maintain muscle mass by restoring immune homeostasis. These data are consistent with the hypothesis that robust anti-cancer T cell immunity leads to improved muscle health. As a first step, this study aims to determine if circulating T cell subsets correlate with muscle strength in people with cancer. Methods The frequency(freq) of T cell subsets was quantified in 11 men with gastrointestinal cancer, and 9 men without cancer, using flow cytometry. Total PBMC protein and gene expression was analyzed using qPCR and Western blots. Clinical measures were assessed using: DEXA scan (body composition); Hand-grip (HGS) test and Knee extension test (Muscle Strength); Stair Climb test (Performance) and Karnofsky and ECOG scales (functional impairment). Data was analyzed using Spearman’s correlation and ANOVA. Results Our data show significant correlations between i) higher freq of CD8 naïve and EM T cells, and lower freq of CD8 CM T cells with stronger HGS, ii) lower freq of Tregs with greater lean mass index, iii) lower freq of CD8 cells expressing CD95 with greater Stair Climb Power, iv) higher freq of CD197+CD45RA+ T cells and greater knee extension strength, and iv) higher expression of CD4 in whole blood with greater functional impairment in people with cancer. Conclusions We have identified significant correlations between levels of T cell populations and muscle strength, performance, and body composition in people with cancer.

Evaluation of Limb Muscle Strength and Function in People With Chronic Obstructive Pulmonary Disease

Purpose: Muscle weakness is an observable consequence of limb muscle dysfunction in people with chronic obstructive pulmonary disease (COPD). The purpose of this review is to describe clinically applicable methods of muscle strength testing and functional tests that are associated with muscle strength in people with COPD. Summary of Key Points: Several tests and devices for evaluating muscle strength have been described in COPD. Isometric quadriceps strength testing, which is associated with clinical outcomes in COPD, can be reliably tested using fixed dynamometers or strain gauges in clinical and laboratory settings. Functional tests that are correlated with muscle strength in COPD include the Stair Climb Power Test, Sit-to-Stand test, and Timed Up and Go test. These tests are easy to conduct in the clinical setting and are relevant to daily activities; however, performance depends on factors such as balance and coordination in addition to leg muscle strength. Conclusions: Muscle strength assessment should be considered an integral part of the evaluation of people with COPD. Clinicians and researchers can select from a variety of valid and reliable tests to evaluate muscle strength based on their available resources and goals of the patient.

Functional Tests of Leg Muscle Strength and Power in Adults With Cystic Fibrosis.

Muscle weakness is an important systemic consequence in adults with cystic fibrosis, but it can be challenging to evaluate clinically. This study examined the validity of lower-extremity functional tests to assess quadriceps muscle strength and muscle power. The subjects underwent 4 functional tests: 30-s sit-to-stand test, stair-climb power test, vertical jump height, and triple hop distance. Quadriceps muscle strength and power were tested by using a dynamometer (the accepted standard). Quadriceps strength was measured from 5 maximum voluntary isometric contractions to obtain peak torque. Quadriceps power was evaluated from the peak power and peak velocity attained during isotonic contractions of the quadriceps at a preset load of 20% of the peak torque. Pearson correlations were used to determine associations between functional tests and accepted measures of quadriceps strength and power. Fifteen adults with cystic fibrosis (9 males; mean ± SD age, 32 ± 13 y; mean ± SD FEV1% predicted, 73 ± 19) completed the study. The stair-climb power test had the strongest correlations with peak torque (r = 0.84, P < .001) and power (r = 0.65, P = .009). Vertical jump height was moderately correlated with quadriceps strength (r = 0.62, P = .014) and quadriceps peak power (r = 0.51, P = .048). Similarly, triple hop distance had moderate correlations with quadriceps strength (r = 0.78, P = .001) and peak power (r = 0.57, P = .026). The sit-to-stand test was only associated with quadriceps strength (r = 0.55, P = .034). Functional tests can be applied clinically to measure leg muscle strength and power, with the stair-climb power test having the strongest associations with the standard measures. The utility of using functional tests to evaluate longitudinal changes in muscle function and its association with clinical outcomes should be examined in cystic fibrosis.

Effect of Protein Intake on Lean Body Mass in Functionally Limited Older Men

The Institute of Medicine set the recommended dietary allowance (RDA) for protein at 0.8 g/kg/d for the entire adult population. It remains controversial whether protein intake greater than the RDA is needed to maintain protein anabolism in older adults. To investigate whether increasing protein intake to 1.3 g/kg/d in older adults with physical function limitations and usual protein intake within the RDA improves lean body mass (LBM), muscle performance, physical function, fatigue, and well-being and augments LBM response to a muscle anabolic drug. This randomized clinical trial with a 2 × 2 factorial design was conducted in a research center. A modified intent-to-treat analytic strategy was used. Participants were 92 functionally limited men 65 years or older with usual protein intake less thanor equal to 0.83 g/kg/d within the RDA. The first participant was randomized on September 21, 2011, and the last participant completed the study on January 19, 2017. Participants were randomized for 6 months to controlled diets with 0.8 g/kg/d of protein plus placebo, 1.3 g/kg/d of protein plus placebo, 0.8 g/kg/d of protein plus testosterone enanthate (100 mg weekly), or 1.3 g/kg/d of protein plus testosterone. Prespecified energy and protein contents were provided through custom-prepared meals and supplements. The primary outcome was change in LBM. Secondary outcomes were muscle strength, power, physical function, health-related quality of life, fatigue, affect balance, and well-being. Among 92 men (mean [SD] age, 73.0 [5.8] years), the 4 study groups did not differ in baseline characteristics. Changes from baseline in LBM (0.31 kg; 95% CI, -0.46 to 1.08 kg; P = .43) and appendicular (0.04 kg; 95% CI, -0.48 to 0.55 kg; P = .89) and trunk (0.24 kg; 95% CI, -0.17 to 0.66 kg; P = .24) lean mass, as well as muscle strength and power, walking speed and stair-climbing power, health-related quality of life, fatigue, and well-being, did not differ between men assigned to 0.8 vs 1.3 g/kg/d of protein regardless of whether they received testosterone or placebo. Fat mass decreased in participants given higher protein but did not change in those given the RDA: between-group differences were significant (difference, -1.12 kg; 95% CI, -2.04 to -0.21; P = .02). Protein intake exceeding the RDA did not increase LBM, muscle performance, physical function, or well-being measures or augment anabolic response to testosterone in older men with physical function limitations whose usual protein intakes were within the RDA. The RDA for protein is sufficient to maintain LBM, and protein intake exceeding the RDA does not promote LBM accretion or augment anabolic response to testosterone. clinicaltrials.gov Identifier: NCT01275365.

Testosterone does not affect agrin cleavage in mobility-limited older men despite improvement in physical function.

In a subset of men, sarcopenia and physical dysfunction occur due to destabilization of the neuromuscular junction (NMJ), which is manifested by elevated serum concentrations of C-terminal agrin fragment (CAF). Testosterone administration improves physical function in some studies; however, its effects on serum circulating CAF concentrations remain unknown. Here we evaluate the effects of testosterone administration on circulating CAF levels in mobility-limited men with low testosterone aged 65 or older participating in the Testosterone in Older Men with Mobility Limitations (TOM) Trial. We analyzed the difference in change in serum CAF levels between testosterone and placebo groups, as well as its association with muscle strength and physical function. Association of change in serum CAF levels with serum total (TT) and free testosterone (FT) was also evaluated. Men randomized to testosterone experienced significant improvement in muscle strength and physical function (assessed by loaded stair-climbing power). However; testosterone administration was not associated with a reduction in serum CAF levels (effect size=-50.3pm; 95% CI=-162.1 to 61.5pm; p=0.374); there was no association between changes in CAF levels with changes in TT (p=0.670) or FT (p=0.747). There was no association between changes in serum CAF levels with improvement in either muscle strength or stair-climbing power. In conclusion, testosterone treatment in mobility-limited older men with low to low-normal testosterone levels did not reduce serum CAF levels. Additionally, testosterone-induced improvements in muscle strength and physical function were not associated with changes in serum CAF concentrations. These findings suggest that improvement in physical function with testosterone replacement in older men with mobility limitations and elevated CAF levels is mediated by mechanisms other than stabilization of the NMJ.

Reliability, Validity, and Minimal Detectable Change of Four-Step Stair Climb Power Test in Community-Dwelling Older Adults.

Stair climb power is an important clinical measure of lower-extremity power. The stair climb power test (SCPT) was validated by requiring individuals to climb a full flight of stairs. A 4-step SCPT (4SCPT) would be more clinically feasible and easier to perform, yet its reliability and validity are unknown. To evaluate reliability, validity, and minimal detectable change of 4SCPT among community-dwelling older adults. This study is a cross-sectional analysis of baseline data from a clinical trial. Fifty older adults ≥65 years of age, at risk for mobility decline, consented to participate in this ancillary study. Test-retest reliability was derived from 2 measurements within each participant measured by a single assessor. Pearson correlation analyses among leg power measures (4SCPT, SCPT, single leg press power at 40% and 70% of the 1-repetition maximum [SLP40, SLP70]) were performed. Separate multivariate linear regressions were conducted evaluating the associations between each leg power measure and 2 mobility outcomes, the Short Physical Performance Battery (SPPB) and habitual gait speed (HGS). Minimal detectable change was based on a 90% confidence interval (MDC 90 ). The 4SCPT had excellent test-retest reliability (ICC(2,1) = 0.951), and strong correlation with SCPT, SLP40, and SLP70 ( r = 0.85-0.96). The 4SCPT explained a greater amount of variance in the SPPB (R 2 = 0.31) than other leg power measurements (R 2 = 0.23-0.25). The 4SCPT (R 2 = 0.41) and SCPT (R 2 = 0.42) described equivalent amounts of variance in HGS, and greater than that with SLP40 (R 2 = 0.28) and SLP70 (R 2 = 0.30). The MDC 90 for 4SCPT was 44.0 watts. This was a cross-sectional analysis within a small, nonrepresentative sample. Interrater reliability was not evaluated. The 4SCPT shows scientific promise as a valid and reliable leg power measurement among community-dwelling older adults.

Post-Acute Rehabilitation After Total Knee Replacement: A Multicenter Randomized Clinical Trial Comparing Long-Term Outcomes.

To evaluate the long-term benefit of providing a post-acute, outpatient group exercise program for patients following primary total knee replacement (TKR) surgery for osteoarthritis. A multicenter randomized clinical trial was conducted in 12 Australian public and private hospital centers. A total of 422 participants, ages 45-75 years, were randomly allocated prior to hospital discharge to the post-acute group exercise program or to usual care and were assessed at 6 weeks, 6 months, and 12 months after surgery. The main outcomes were operated knee pain and activity limitations at 12 months using the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire. Secondary outcomes included health-related quality of life (Short Form 12 health survey), knee extension and flexion strength, stair-climb power, 50-foot walk speed, and active knee range of motion. While both allocation groups achieved significant improvements in knee pain and activity limitations over the 12-month followup period, there were no significant differences in these main outcomes, or in the secondary physical performance measures, between the 2 treatment allocations. Twelve months after TKR, 69% and 72% of participants allocated to post-acute exercise and usual acute care, respectively, were considered to be treatment-responders. While population normative values for self-report measures of pain, activity limitation, and health-related quality of life were attained 12 months after TKR, marked deficits in physical performance measures remained. Providing access to a post-acute group exercise program did not result in greater reductions in long-term knee pain or activity limitations than usual care. Patients undergoing primary TKR retain marked physical performance deficits 12 months after surgery.