Physiological determinants of mechanical efficiency during advanced ageing and disuse.

This study aimed to determine which physiological factors impact net efficiency (ηnet) in oldest-old individuals at different stages of skeletal muscle disuse. To this aim, we examined ηnet, central haemodynamics, peripheral circulation, and peripheral factors (skeletal muscle fibre type, capillarization and concentration of mitochondrial DNA [mtDNA]). Twelve young (YG; 25 ± 2 years), 12 oldest-old mobile (OM; 87 ± 3 years), and 12 oldest-old immobile (OI; 88 ± 4 years) subjects performed dynamic knee extensor (KE) and elbow flexors (EF) exercise. Pulmonary oxygen uptake, photoplethysmography, Doppler ultrasound and muscle biopsies of the vastus lateralis and biceps brachii were used to assess central and peripheral adaptations to advanced ageing and disuse. Compared to the YG (12.1 ± 2.4%), the ηnet of lower-limb muscle was higher in the OM (17.6 ± 3.5%, P < 0.001), and lower in the OI (8.9 ± 1.9%, P < 0.001). These changes in ηnet during KE were coupled with significant peripheral adaptations, revealing strong correlations between ηnet and the proportion of type I muscle fibres (r = 0.82), as well as [mtDNA] (r = 0.77). No differences in ηnet were evident in the upper-limb muscles between YG, OM and OI. In view of the differences in limb-specific activity across the lifespan, these findings suggest that ηnet is reduced by skeletal muscle inactivity and not by chronological age, per se. Likewise, this study revealed that the age-related changes in ηnet are not a consequence of central or peripheral haemodynamic adaptations, but are likely a product of peripheral changes related to skeletal muscle fibre type and mitochondrial density. KEY POINTS: Although the effects of ageing and muscle disuse deeply impact the cardiovascular and skeletal muscle function, the combination of these factors on the mechanical efficiency are still a matter of debate. By measuring both upper- and lower-limb muscle function, which experience differing levels of disuse, we examined the influence of central and peripheral haemodynamics, and skeletal muscle factors linked to mechanical efficiency. Across the ages and degree of disuse, upper-limb muscles exhibited a preserved work economy. In the legs the oldest-old without mobility limitations exhibited an augmented mechanical efficiency, which was reduced in those with an impairment in ambulation. These changes in mechanical efficiency were associated with the proportion of type I muscle fibres. Recognition that the mechanical efficiency is not simply age-dependent, but the consequence of inactivity and subsequent skeletal muscle changes, highlights the importance of maintaining physical activity across the lifespan.

A Feasibility Study Investigating an Exercise Program in Metastatic Cancer Based on the Patient-Preferred Delivery Mode.

BACKGROUND: Feasibility of exercise in patients with metastatic cancer is still a challenge. This study aimed to determine the feasibility and preliminary efficacy of an exercise intervention based on a patient-preferred delivery mode in patients affected by metastatic cancer. MATERIALS AND METHODS: Forty-four patients with a confirmed diagnosis of metastatic cancer were recruited in a 3-month exercise program. Whereas the exercise program consisted of aerobic and resistance activities performed twice a week, the participants may choose the mode of delivery: home based, personal training, or group based. The primary endpoint was the feasibility, defined by recruitment rate, attendance, adherence, dropout rate, tolerability (comparing the session RPE with the target RPE), and safety (using the Common Terminology Criteria for Adverse Events, version 5.0). Secondary endpoints included cardiorespiratory fitness (six minutes walking test), muscle strength (handgrip strength test and isometric leg press test), flexibility (the back scratch and chair sit and reach tests), anthropometric parameters (body mass index and waist-hip ratio), quality of life (EORTC QLQ C-30 questionnaire), and amount of physical exercise (Godin's Shepard Leisure Time Exercise Questionnaire). Descriptive statistics, Student t test, and Wilcoxon signed rank test were used to analyze data. RESULTS: The study recruitment rate was 81%. Out of 44 recruited patients, 28 chose the personal training program, 16 chose the home-based program, and none chose the group-based program. Nine dropouts occurred (20%), 6 in the personal training program, and 3 in the home-based intervention. The median attendance rate was 92%, adherence was 88%, tolerability was 100%, and 9 nonsevere adverse events were registered during the exercise sessions. An increase in cardiorespiratory fitness (P < .001) and flexibility (P = .011 for chair sit and reach; P = .040 for back scratch) was observed at the end of the intervention, while no changes in anthropometric values and muscle strength were detected. Different quality-of-life domains were improved following the intervention, including physical (P = .002), emotional (P < .001), and role functioning (P = .018), fatigue (P = .030), and appetite loss (P = .005). CONCLUSION: A 3-month exercise program based on a patient-preferred delivery mode is feasible in patients with metastatic cancer and may improve physical function and quality of life. TRIAL REGISTRATION: NCT04226508.

Skeletal muscle fiber type and TMS-induced muscle relaxation in unfatigued and fatigued knee-extensor muscles.

The force drop after transcranial magnetic stimulation (TMS) delivered to the motor cortex during voluntary muscle contractions could inform about muscle relaxation properties. Because of the physiological relation between skeletal muscle fiber-type distribution and size and muscle relaxation, TMS could be a noninvasive index of muscle relaxation in humans. By combining a noninvasive technique to record muscle relaxation in vivo (TMS) with the gold standard technique for muscle tissue sampling (muscle biopsy), we investigated the relation between TMS-induced muscle relaxation in unfatigued and fatigued states, and muscle fiber-type distribution and size. Sixteen participants (7F/9M) volunteered to participate. Maximal knee-extensor voluntary isometric contractions were performed with TMS before and after a 2-min sustained maximal voluntary isometric contraction. Vastus lateralis muscle tissue was obtained separately from the participants' dominant limb. Fiber type I distribution and relative cross-sectional area of fiber type I correlated with TMS-induced muscle relaxation at baseline (r = 0.67, adjusted P = 0.01; r = 0.74, adjusted P = 0.004, respectively) and normalized TMS-induced muscle relaxation as a percentage of baseline (r = 0.50, adjusted P = 0.049; r = 0.56, adjusted P = 0.031, respectively). The variance in the normalized peak relaxation rate at baseline (59.8%, P < 0.001) and in the fatigue resistance (23.0%, P = 0.035) were explained by the relative cross-sectional area of fiber type I to total fiber area. Fiber type I proportional area influences TMS-induced muscle relaxation, suggesting TMS as an alternative method to noninvasively inform about skeletal muscle relaxation properties.NEW & NOTEWORTHY Transcranial magnetic stimulation (TMS)-induced muscle relaxation reflects intrinsic muscle contractile properties by interrupting the drive from the central nervous system during voluntary muscle contractions. We showed that fiber type I proportional area influences the TMS-induced muscle relaxation, suggesting that TMS could be used for the noninvasive estimation of muscle relaxation in unfatigued and fatigued human muscles when the feasibility of more direct method to study relaxation properties (i.e., muscle biopsy) is restricted.

Decreased neural drive affects the early rate of force development after repeated burst-like isometric contractions.

The neural drive to the muscle is the primary determinant of the rate of force development (RFD) in the first 50 ms of a rapid contraction. It is still unproven if repetitive rapid contractions specifically impair the net neural drive to the muscles. To isolate the fatiguing effect of contraction rapidity, 17 male adult volunteers performed 100 burst-like (i.e., brief force pulses) isometric contractions of the knee extensors. The response to electrically-evoked single and octet femoral nerve stimulation was measured with high-density surface electromyography (HD-sEMG) from the vastus lateralis and medialis muscles. Root mean square (RMS) of each channel of HD-sEMG was normalized to the corresponding M-wave peak-to-peak amplitude, while muscle fiber conduction velocity (MFCV) was normalized to M-wave conduction velocity to compensate for changes in sarcolemma properties. Voluntary RFD 0-50 ms decreased (d = -0.56, p < 0.001) while time to peak force (d = 0.90, p < 0.001) and time to RFDpeak increased (d = 0.56, p = 0.034). Relative RMS (d = -1.10, p = 0.006) and MFCV (d = -0.53, p = 0.007) also decreased in the first 50 ms of voluntary contractions. Evoked octet RFD 0-50 ms (d = 0.60, p = 0.020), M-wave amplitude (d = 0.77, p = 0.009) and conduction velocity (d = 1.75, p < 0.001) all increased. Neural efficacy, i.e., voluntary/octet force ratio, largely decreased (d = -1.50, p < 0.001). We isolated the fatiguing impact of contraction rapidity and found that the decrement in RFD, particularly when calculated in the first 50 ms of muscle contraction, can mainly be explained by a decrease in the net neural drive.

Non-specific and ski-specific performance development in peri-pubertal cross-country skiers.

PURPOSE: To evaluate non-specific and ski-specific performance development in male (M) and female (F) peri-pubertal cross-country skiers and to evaluate their relationship with cross-country skiing (XCS) performance and biological maturation within each age category and sex. METHODS: Twenty-one and 19 athletes under 14 and 16 years old, respectively (U14 and U16), were tested for biological maturation; non-specific speed, agility, strength, endurance, and balance; ski-specific speed, agility, and endurance. XCS index was considered as average percentage time-gap from the winner in four official races. Sex and age-category effects were verified and a model predicting XCS index was extrapolated for each group. RESULTS: Performance capacities raised across age categories (p < 0.05) except for non-specific speed, agility, balance, and relative arm strength (p > 0.05). F showed advanced biological maturation and greater balance than M (p < 0.05), while M showed higher performance capacities (p < 0.05). XCS index was not related to biological maturation within each group (p > 0.05); its variance was explained by non-specific speed and ski-specific upper-body endurance in M-U14 (p = 0.014), lower-limb strength and ski-specific agility in M-U16 and F-U14 (both p = 0.001), ski-specific upper-body endurance in F-U16 (p = 0.002). CONCLUSION: Ski-specific performance capacities still develop during peri-puberty, with peri-pubertal M overperforming with respect to F of comparable performance level. XCS index was not influenced by biological maturation withing each age category, but it was rather explained by specific parameters that commonly undergo the "adolescent spurts", accordingly to the average biological maturation level of M and F athletes of each age category.

Central and peripheral haemodynamics at exercise onset: the role of central command.

PURPOSE: The involvement of central command in central hemodynamic regulation during exercise is relatively well-known, although its contribution to peripheral hemodynamics at the onset of low-intensity contractions is debated. This study sought to examine central and peripheral hemodynamics during electrically-evoked muscle contractions (without central command) and voluntary muscle activity (with central command). METHODS: Cyclic quadriceps isometric contractions (1 every second), either electrically-evoked (ES; 200 ms trains composed of 20 square waves) or performed voluntarily (VC), were executed by 10 healthy males (26 ± 3 years). In both trials, matched for force output, peripheral and central hemodynamics were analysed. RESULTS: At exercise onset, both ES and VC exhibited equal peaks of femoral blood flow (1276 ± 849 vs. 1117 ± 632 ml/min, p > 0.05) and vascular conductance (15 ± 11 vs. 13 ± 7 ml/min/mmHg, p > 0.05), respectively. Similar peaks of heart rate (86 ± 16 bpm vs. 85 ± 16 bpm), stroke volume (100 ± 20 vs. 99 ± 27 ml), cardiac output (8.2 ± 2.5 vs. 8.5 ± 2.1 L/min), and mean arterial pressure (113 ± 13 vs. 113 ± 3 mmHg), were recorded (all, p > 0.05). After ~ 50 s, all the variables drifted to lower values. Collectively, the hemodynamics showed equal responses. CONCLUSION: These results suggest a similar pathway for the initial (first 40 s) increase in central and peripheral hemodynamics. The parallel responses may suggest an initial minimal central command involvement during the onset of low-intensity contractions, likely associated with a neural drive activation delay or threshold.

Interferon regulatory factor 7 impairs cellular metabolism in aging adipose-derived stromal cells.

Dysregulated immunity and widespread metabolic dysfunctions are the most relevant hallmarks of the passing of time over the course of adult life, and their combination at midlife is strongly related to increased vulnerability to diseases; however, the causal connection between them remains largely unclear. By combining multi-omics and functional analyses of adipose-derived stromal cells established from young (1 month) and midlife (12 months) mice, we show that an increase in expression of interferon regulatory factor 7 (IRF7) during adult life drives major metabolic changes, which include impaired mitochondrial function, altered amino acid biogenesis and reduced expression of genes involved in branched-chain amino acid (BCAA) degradation. Our results draw a new paradigm of aging as the 'sterile' activation of a cell-autonomous pathway of self-defense and identify a crucial mediator of this pathway, IRF7, as driver of metabolic dysfunction with age.

Circadian and sex differences in post-ischemic vasodilation and reactive hyperemia in young individuals and elderly with and without type 2 diabetes.

OBJECTIVE: Cardiovascular events show morning preference and sex differences, and are related to aging and type 2 diabetes. We assessed circadian variations and sex differences in vascular conductance (VC) and blood flow (BF) regulations following a brief bout of forearm ischemia. METHODS: Young healthy individuals (H18-30) and elderly without (H50-80) and with type 2 diabetes (T2DM50-80) of both sexes were included. Forearm VC and BF, and mean arterial pressure (MAP) at baseline and following circulatory reperfusion were measured at 6 a.m. and 9 p.m. RESULTS: In the morning compared to evening, following reperfusion, the VC and BF increments were similar in H18-30 (p>.71), but lower in H50-80 (p<.001) and T2DM50-80 (p<.01). VC and BF following circulatory reperfusion were higher in men than women in H18-30 (p<.001), but similar between sexes in the older groups (p>.23). CONCLUSIONS: Forearm vasodilation following reperfusion is attenuated in the morning in the elderly, impairing BF towards an ischemic area. Diabetes does not affect the circadian regulation of VC and BF, but that of MAP. There are sex differences in VC and BF at baseline and after circulatory reperfusion at a young age, being greater in men, which disappear with aging without being affected by diabetes.

Effect of exercise across the head and neck cancer continuum: a systematic review of randomized controlled trials.

PURPOSE: This study aims to systematically explore the impact of physical exercise as supportive therapy for head and neck cancer. METHODS: A systematic search on PubMed/MEDLINE, Cochrane, and SPORTDiscus was conducted. Randomized controlled trials exploring the effects of a physical exercise intervention in comparison with usual care on outcomes in patients with head and neck cancer were selected. The RoB 2 tool was used to determine the study quality. The extracted data are reported as qualitative synthesis. RESULTS: Among the 527 records examined, nine studies were included. No trials investigating exercise as prehabilitation were found, whereas eight studies involving 452 patients with head and neck cancer were conducted during anticancer treatment. Most trials did not report improvements in body mass index or body composition, while 2/4 and 3/5 investigations found a significant increase in muscle strength and cardiorespiratory fitness, respectively. Regarding the patients' reported outcomes, 4 out of 7 studies observed enhancements in some domains of quality of life, and two trials out of 3 detected an amelioration in fatigue following the exercise intervention. Analyzing the exercise programs, it seems that combining aerobic and resistance training could be more beneficial compared to a single type of full-body exercise in counteracting physical decline and controlling symptoms in the anticancer therapy phase. One trial has investigated the effect of resistance exercise on patients who had terminated the anticancer treatments, reporting significant improvements in lean mass, muscle strength, and quality of life. CONCLUSION: Exercise may be a promising approach in patients with head and neck cancer. Future studies are needed to consolidate these results.

A novel echocardiography method to assess upper body systemic blood flow in preterm infants and comparison with superior vena cava flow measurement.

To evaluate feasibility, reproducibility, and prognostic value of a new echocardiographic method to assess systemic arterial blood flow directed to the upper part of the body (UBAF, upper body arterial flow) alternative to superior vena cava flow (SVCF) measurement. We performed echocardiographic evaluations in 106 infants in the first 2 days of life to obtain SVCF, left ventricle output (LVO), UBAF, and standard parameters of patent ductus arteriosus (PDA) significance. UBAF was calculated by subtracting from LVO the aortic arch blood flow measured immediately distally to the origin of the left subclavian artery. Main outcome measures: UBAF and SVCF agreement was assessed by Bland-Altman analysis in terms of bias, limits of agreement and repeatability index. The Intraclass Correlation Coefficient was used to measure the strength of inter-rater agreement. The agreement between UBAF and SVCF was high. The Concordance Correlation Coefficient (CCC) was 0.7434. (CCC 0.7434, 95% C.I. [0.656, 0.8111]). There was a good absolute agreement between the two raters ICC = 0.747; p value < 0.0001; 95%CI [0.601; 0.845]. Adjusting for confounding factors (BW, GA, PDA) included in the model, there was a statistically significant relationship between UBAF and SVCF. CONCLUSION: UBAF showed a strong agreement with the SCVF with a better reproducibility. Our data support UBAF as a potentially useful marker of cerebral perfusion in the evaluation of preterm infants. WHAT IS KNOWN: • Low SVC (superior vena cava) flow in the neonatal period has been associated with periventricular haemorrhage and unfavourable long-term neurodevelopmental outcome. • Ultrasound measurement of flow in SVC shows relatively high inter-operator variability. WHAT IS NEW: • Our study highlights how much overlap there is between upper-body arterial flow (UBAF) measurement and SCV flow measurement. UBAF is easier to perform and has a strong correlation with better reproducibility. • UBAF may replace measurement of cava flow as a method for haemodynamic monitoring of unstable preterm and asphyxiated infants.

Neural and contractile determinants of burst-like explosive isometric contractions of the knee extensors.

Walking and running are based on rapid burst-like muscle contractions. Burst-like contractions generate a Gaussian-shaped force profile, in which neuromuscular determinants have never been assessed. We investigated the neural and contractile determinants of the rate of force development (RFD) in burst-like isometric knee extensions. Together with maximal voluntary force (MVF), voluntary and electrically evoked (8 stimuli at 300 Hz, octets) forces were measured in the first 50, 100, and 150 ms of burst-like quadriceps contractions in 24 adults. High-density surface electromyography (HDsEMG) was adopted to measure the root mean square (RMS) and muscle fiber conduction velocity (MFCV) from the vastus lateralis and medialis. The determinants of voluntary force at 50, 100, and 150 ms were assessed by stepwise multiple regression analysis. Force at 50 ms was explained by RMS (R2  = 0.361); force at 100 ms was explained by octet (R2  = 0.646); force at 150 ms was explained by MVF (R2  = 0.711) and octet (R2  = 0.061). Peak RFD (which occurred at 60 ± 10 ms from contraction onset) was explained by MVF (R2  = 0.518) and by RMS50 (R2  = 0.074). MFCV did not emerge as a determinant of RFD. Muscle excitation was the sole determinant of early RFD (50 ms), while contractile characteristics were more relevant for late RFD (≥100 ms). As peak RFD is mostly determined by MVF, it may not be more informative than MVF itself. Therefore, a time-locked analysis of RFD provides more insights into the neuromuscular characteristics of explosive contractions.

Do poles really "save the legs" during uphill pole walking at different intensities?

PURPOSE: In sky- and trail-running competitions, many athletes use poles. The aims of this study were to investigate whether the use of poles affects the force exerted on the ground at the feet (Ffoot), cardiorespiratory variables and maximal performance during uphill walking. METHODS: Fifteen male trail runners completed four testing sessions on different days. On the first two days, they performed two incremental uphill treadmill walking tests to exhaustion with (PWincr) and without poles (Wincr). On the following days, they performed submaximal and maximal tests with (PW80 and PWmax) and without (W80 and Wmax) poles on an outdoor trail course. We measured cardiorespiratory parameters, the rating of perceived exertion, the axial poling force and Ffoot. RESULTS: When walking on the treadmill, we found that poles reduced maximum Ffoot (- 2.8 ± 6.4%, p = 0.03) and average Ffoot (- 2.4 ± 3.3%, p = 0.0089). However, when outdoors, we found pole effect only for average Ffoot (p = 0.0051), which was lower when walking with poles (- 2.6 ± 3.9%, p = 0.0306 during submaximal trial and - 5.21 ± 5.51%, p = 0.0096 during maximal trial). We found no effects of poles on cardiorespiratory parameters across all tested conditions. Performance was faster in PWmax than in Wmax (+ 2.5 ± 3.4%, p = 0.025). CONCLUSION: The use of poles reduces the foot force both on the treadmill and outdoors at submaximal and maximal intensities. It is, therefore, reasonable to conclude that the use of poles "saves the legs" during uphill without affecting the metabolic cost.

The role of muscle mass in vascular remodeling: insights from a single-leg amputee model.

PURPOSE: Both muscle mass and physical activity are independent mechanisms that play a role in vascular remodeling, however, the direct impact of muscle mass on the structure and function of the vessels is not clear. The aim of the study was to determine the impact of muscle mass alteration on lower limbs arterial diameter, blood flow, shear rate and arterial stiffness. METHODS: Nine (33 ± 13 yrs) male individuals with a single-leg amputation were recruited. Vascular size (femoral artery diameter), hemodynamics (femoral artery blood flow and shear rate were measured at the level of the common femoral artery in both amputated (AL) and whole limbs (WL). Muscle mass of both limbs, including thigh for AL and thigh and leg for WL, was measured with a DXA system. RESULTS: AL muscle mass was reduced compared to the WL (3.2 ± 1.2 kg vs. 9.4 ± 2.1 kg; p = 0.001). Diameter of the femoral artery was reduced in the AL (0.5 ± 0.1 cm) in comparison to the WL (0.9 ± 0.2 cm, p = 0.001). However, femoral artery blood flow normalized for the muscle mass (AL = 81.5 ± 78.7ml min-1 kg-1,WL = 32.4 ± 18.3; p = 0.11), and blood shear rate (AL = 709.9 ± 371.4 s-1, WL = 526,9 ± 295,6; p = 0.374) were non different between limbs. A correlation was found only between muscle mass and femoral artery diameter (p = 0.003, R = 0.6561). CONCLUSION: The results of this study revealed that the massive muscle mass reduction caused by a leg amputation, but independent from the level of physical activity, is coupled by a dramatic arterial diameter decrease. Interestingly, hemodynamics and arterial stiffness do not seem to be impacted by these structural changes.

Perinatal asphyxia partly affects presepsin urine levels in non-infected term infants.

OBJECTIVES: Standard of care sepsis biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT) can be affected by several perinatal factors, among which perinatal asphyxia (PA) has a significant role. In this light, new early sepsis biomarkers such as presepsin (P-SEP) are needed to enact therapeutic strategies at a stage when clinical and laboratory patterns are still silent or unavailable. We aimed at investigating the potential effects of PA on longitudinal P-SEP urine levels. METHODS: We conducted an observational case-control study in 76 term infants, 38 with PA and 38 controls. Standard clinical, laboratory, radiological monitoring procedures and P-SEP urine measurement were performed at four time-points (first void, 24, 48, 96 h) after birth. RESULTS: Higher (p<0.05) CRP and PCT blood levels at T1-T3 were observed in PA than control infants whilst no differences (p>0.05, for all) at T0 were observed between groups. P-SEP urine levels were higher (p<0.05) in PA at first void and at 24 h while no differences (p>0.05) at 48 and 96 h were observed. No significant correlations were found (p>0.05) between P-SEP and urea (R=0.11) and creatinine (R=0.02) blood levels, respectively. CONCLUSIONS: The present results, showed that PA effects on P-SEP were limited up to the first 24 h following birth in absence of any kidney function bias. Data open the way to further investigations aimed at validating P-SEP assessment in non-invasive biological fluids as a reliable tool for early EOS and LOS detection in high-risk infants.

Is handgrip strength a marker of muscle and physical function of the lower limbs? Sex differences in older adults with obesity.

BACKGROUND AND AIMS: In this cross-sectional study we investigate the association between handgrip strength (HGS) and muscle function of the lower limbs and the predictors of the appendicular lean mass index (ALMI) in older adults with obesity of both sexes. METHODS AND RESULTS: Eighty-four older (67 ± 5 years) men (N = 44) and women (N = 40) with obesity (body mass index (BMI) 33 ± 4 kg/m2) performed: the HGS, isokinetic knee extensors (KE) and flexors (KF) muscle strength and power and Short Physical Performance Battery (SPPB). The correlation between HGS and lower limbs muscle function was evaluated, and four multiple hierarchical linear models were built to assess the contribution of each ALMI predictor (i.e., HGS, BMI, SPPB, muscle strength and power). In men, HGS was weakly-to-moderately associated (p < 0.05) with KE, KF muscle function and physical performance. In women, HGS showed a weak association (p < 0.05) with KE muscle function. The significant predictors of ALMI were only the BMI in women, whereas in the group of men BMI, KE maximal strength and power better explain the variance in ALMI than HGS alone. CONCLUSION: Our results suggest that HGS should not be used alone as a marker of lower muscle nor physical function. Sex differences exist with the BMI that is a contributor of ALMI both in men and women. However, at least in the group of men, markers related to strength and power of the lower limbs can better describe variations in ALMI compared to HGS in this kind of population. CLINICAL TRIAL REGISTRATION: NA.

Relationship between perceived and neuromuscular fatigue in COPD patients with chronic respiratory failure with long-term oxygen therapy: a cross-sectional study.

PURPOSE: To evaluate perceived fatigue (PF) and neuromuscular fatigue (NMF) in patients with COPD and chronic respiratory failure (CRF) on long-term oxygen therapy (CRF-COPD group), and the relationships between PF, NMF, patient's characteristics, comparing severe patients with COPD to patients without CRF (COPD group). METHODS: This cross-sectional study compared 19 CRF-COPD patients with 10 COPD patients attending a rehabilitation program. PF was determined by Fatigue Severity Scale (FSS), while dyspnea by the Barthel Dyspnea Index (BDI). We assessed quadriceps NMF via electrical nerve stimulation during and following a Maximal Voluntary Contraction (MVC) detecting changes after a Constant Workload Cycling Test (CWCT) at 80% of the peak power output at exhaustion. RESULTS: CRF-COPD patients showed higher PF (+ 1.79 of FSS score, p = 0.0052) and dyspnea (+ 21.03 of BDI score, p = 0.0023) than COPD patients. After the fatiguing task and normalization for the total work, there was a similar decrease in the MVC (CRF-COPD -1.5 ± 2.4 vs COPD -1.1 ± 1.2% baseline kJ-1, p = 0.5819), in the potentiated resting twitch force (CRF-COPD -2.8 ± 4.7 vs COPD -2.0 ± 3.3% baseline kJ-1, p = 0.7481) and in the maximal voluntary activation (CRF-COPD -0.1 ± 3.9 vs COPD -0.9 ± 1.2 -2.0 ± 3.3% baseline kJ-1, p = 0.4354). FSS and BDI were closely related (R = 0.5735, p = 0.0011), while no correlation between PF and NMF was found. CONCLUSION: Patients with CRF-COPD develop higher levels of perceived fatigue and dyspnea than patients with COPD; while neuromuscular fatigue is similar, suggesting a mismatch between symptoms and neuromuscular dysfunction.

Knee flexor and extensor torque ratio in elderly men and women with and without obesity: a cross-sectional study.

BACKGROUND: With aging and obesity lower limb torque deteriorates. Importantly, the ratio between knee flexor (KF) and extensor (KE) torque is an indicator of joint stability. AIMS: We compared KF torque and KF/KE ratio in older subjects of both sexes with obesity (OB) or without (NOB) obesity. METHODS: The maximal torque during KE and KF isokinetic contractions were evaluated at: 60, 90, 150, 180 and 210 deg/s in 89 elderly (68 ± 5 years) subjects with NOB (BMI < 30 kg/m2) and OB (BMI ≥ 30 kg/m2). Values were normalised for body weight (BW) and leg lean mass (i.e., muscle quality). RESULTS: At all speeds men had higher absolute KF values (P < 0.001). When values were normalised for BW, sex differences remain in favour of men (P < 0.001) with lower values in both groups with OB than NOB (P < 0.001). Muscle quality and KF/KE ratio were lower in OB than NOB (P < 0.001). CONCLUSIONS: The KF torque and KF/KE ratio decline with aging and with OB. In all groups, the KF/KE ratio was below the joint stability threshold. Thus, exercise physiologists should include exercises designed to train both KE and KF in older subjects with OB.

Eager to set a record in a vertical race? Test your VO2max first!

We investigated the relationship between maximal oxygen consumption (VO2max) and performance in vertical races (VRs). In total, 270 performances, from 26 VRs, and cardiopulmonary data of 64 highly-trained mountain runners (53 M, V O2max: 75.7±5.8 mL/min/kg; 11 F: 65.7±3.4 mL/min/kg), collected over a 11-year period (2012-2022), were analysed. The relationship between performance and VO2max was modelled separately for national (NVRs), international (IVRs), and VRs of current pole-unassisted and pole-assisted vertical kilometre (VK) records (RVRs). Three different (p<0.001) exponential models described the relationship between performance and VO2max in IVRs (R2=0.96, p<0.001), NRs (R2=0.91, p<0.001) and RVRs (R2=0.97, p<0.001). Estimated VO2max requirements (with 95% CI) to win/set a record time in IVRs were 86.2(85.3-87.1)/89.4(88.2-90.5) and 74.0(73.6-74.4)/76.8(76.4-77.3) mL/min/kg, for males and females, respectively, 86.1(85.0-87.1)/90.4(89.0-91.8) and 74.8(74.2-75.3)/77.1(77.6-77.7) mL/min/kg in RVRs, decreasing to 83.7(82.5-84.9)/87.6(86.0-89.2) and 66.8(65.9-67.7)/70.7(70.1-71.4) mL/min/kg in NVRs. Our study also suggested a tendency towards a non-uniform variation in the metabolic demand of off-road running, likely attributable to the different features of the VRs (e.g., terrain, technical level, use of poles). These data provide mean VO2max requirements for mountain runners to win and establish new records in VRs and stimulate new research on the energy cost of off-road running.

Including the Eccentric Phase in Resistance Training to Counteract the Effects of Detraining in Women: A Randomized Controlled Trial.

ABSTRACT: Coratella, G, Beato, M, Bertinato, L, Milanese, C, Venturelli, M, and Schena, F. Including the eccentric phase in resistance training to counteract the effects of detraining in women: a randomized controlled trial. J Strength Cond Res 36(11): 3023-3031, 2022-The current study compared the effects of concentric-based (CONC), eccentric-based (ECC), and traditional concentric-eccentric (TRAD) resistance training on muscle strength, mass, and architecture and the postdetraining retention of the training-induced effects in women. Sixty women were randomly assigned to unilateral volume-equated CONC, ECC, or TRAD knee extension training or control ( N = 15 per group). Before training, after an 8-week intervention period, and after an 8-week detraining period, isokinetic concentric, eccentric, and isometric torque were measured. In addition, thigh lean mass was assessed by dual X-ray absorptiometry and vastus lateralis thickness, pennation angle, and fascicle length by ultrasound. After training, concentric and isometric torque increased ( p < 0.05) similarly in all groups, whereas eccentric torque increased more in ECC than that in CONC (+13.1%, effect size (ES): 0.71 [0.04-1.38]) and TRAD (+12.6%, ES: 0.60 [0.12-1.08]). Thigh lean mass increased in ECC (+6.1%, ES: 0.47 [0.27-0.67]) and TRAD (+3.1%, ES: 0.33 [0.01-0.65]). Vastus lateralis thickness and pennation angle increased ( p < 0.05) similarly in all groups, whereas fascicle elongation was visible in ECC (+9.7%, ES: 0.92 [0.14-1.65]) and TRAD (+7.1%, ES: 0.64 [0.03-1.25]). After detraining, all groups retained ( p < 0.05) similar concentric torque. ECC and TRAD preserved eccentric torque ( p < 0.05), but ECC more than TRAD (+17.9%, ES: 0.61 [0.21-1.21]). All groups preserved isometric torque ( p < 0.05), but ECC more than CONC (+14.2%, ES: 0.71 [0.04-1.38]) and TRAD (+13.8%, ES: 0.65 [0.10-1.20]). Thigh lean mass and vastus lateralis fascicle length were retained only in ECC ( p < 0.05), pennation angle was preserved in all groups ( p < 0.05), and thickness was retained in CONC and ECC ( p < 0.05). Including the eccentric phase in resistance training is essential to preserve adaptations after detraining.

Full characterisation of knee extensors' function in ageing: effect of sex and obesity.

BACKGROUND/OBJECTIVES: Muscle function is a marker of current and prospective health/independence throughout life. The effects of sex and obesity (OB) on the loss of muscle function in ageing remain unresolved, with important implications for the diagnosis/monitoring of sarcopenia. To characterise in vivo knee extensors' function, we compared muscles torque and power with isometric and isokinetic tests in older men (M) and women (W), with normal range (NW) of body mass index (BMI) and OB. SUBJECTS/METHODS: In 70 sedentary older M and W (69 ± 5 years), NW and OB (i.e. BMI < 30 kg m-2 and ≥30 kg m-2, respectively) we tested the right knee's extensor: (i) isometric torque at 30°, 60°, 75° and 90° knee angles, and (ii) isokinetic concentric torque at 60, 90, 150, 180 and 210° s-1 angular speeds. Maximal isometric T-angle, maximal isokinetic knee-extensor torque-velocity, theoretical maximal shortening velocity, maximal power, optimal torque and velocity were determined in absolute units, normalised by body mass (BM) and right leg lean mass (LLMR) and compared over sex, BMI categories and angle or angular speeds by three-way ANOVA. RESULTS: In absolute units, relative to BM and LLMR, sex differences were found in favour of M for all parameters of muscle function (main effect for sex, p < 0.05). OB did not affect either absolute or relative to LLMR isometric and isokinetic muscle function (main effect for BMI, p > 0.05); however, muscle function indices, when adjusted for BM, were lower in both M and W with OB compared to NW counterparts (p < 0.05). CONCLUSIONS: We confirmed sex differences in absolute, relative to BM and LLMR muscle function in favour of men. While overall muscle function and muscle contractile quality is conserved in individuals with class I OB, muscle function normalised for BM, which defines the ability to perform independently and safely the activities of daily living, is impaired in comparison with physiological ageing.