Stroke volume response during prolonged exercise depends on left ventricular filling: evidence from a ß-blockade study.

Prolonged moderate-intensity exercise leads to a progressive upward drift in heart rate (HR) that may compromise stroke volume (SV). Alternatively, the HR drift may be related to abated SV due to impaired ventricular function. The aim of this study was to examine the effects of cardiovascular drift on left ventricular volumes and in turn SV. Thirteen healthy young males completed two 60-min cycling bouts on a semirecumbent cycle ergometer at 57% maximal oxygen consumption (V̇o2max) either under placebo condition (CON) or after ingesting a small dose of ß1-blockers (BB). Measurements of HR, end-diastolic volume (EDV), and end-systolic volume were obtained by echocardiography and used to calculate SV. Other variables such as ear temperature, skin temperature, blood pressure, and blood volume were measured to assess potential changes in thermoregulatory needs and loading conditions. HR drift was successfully prevented when using BB from min 10 to min 60 (128 ± 9 to 126 ± 8 beats/min, P = 0.29) but not in CON (134 ± 10 to 148 ± 10 beats/min, P < 0.01). Conversely, during the same time, SV increased by 13% when using BB (103 ± 9 to 116 ± 7 mL, P < 0.01), whereas it was unchanged in CON (99 ± 7 to 101 ± 9 mL, P = 0.37). The SV behavior was mediated by a 4% increase in EDV in the BB condition (164 ± 18 to 170 ± 18 mL, P < 0.01), whereas no change was observed in the CON condition (162 ± 18 to 160 ± 18 mL, P = 0.23). In conclusion, blocking HR drift enhances EDV and SV during prolonged exercise. These findings suggest that SV behavior is tightly related to filling time and loading conditions of the left ventricle.

Aerobic high-intensity intervals are superior to improve V̇O2max compared with sprint intervals in well-trained men.

Maximal oxygen uptake (V̇O2max ) may be the single most important factor for long-distance running performance. Interval training, enabling high intensity, is forwarded as the format that yields the largest increase in V̇O2max . However, it is uncertain if an optimal outcome on V̇O2max , anaerobic capacity, and running performance is provided by training with a high aerobic intensity or high overall intensity. Thus, we randomized 48 aerobically well-trained men (23 ± 3 years) to three commonly applied interval protocols, one with high aerobic intensity (HIIT) and two with high absolute intensity (sprint interval training; SIT), 3× week for 8 weeks: (1) HIIT: 4 × 4 min at ~95% maximal aerobic speed (MAS) with 3 min active breaks. (2) SIT: 8 × 20 s at ~150% MAS with 10 s passive breaks. (3) SIT: 10 × 30 s at ~175% MAS with 3.5 min active breaks. V̇O2max increased more (p < 0.001) following HIIT, 4 × 4 min (6.5 ± 2.4%, p < 0.001) than SIT, 8 × 20 s (3.3 ± 2.4%, p < 0.001) and SIT, 10 × 30 s (n.s.). This was accompanied by a larger (p < 0.05) increase in stroke volume (O2 -pulse) following HIIT, 4 × 4 min (8.1 ± 4.1%, p < 0.001) compared with SIT, 8 × 20 s (3.8 ± 4.2%, p < 0.01) and SIT, 10 × 30 (n.s.). Anaerobic capacity (maximal accumulated oxygen deficit) increased following SIT, 8 × 20 s (p < 0.05), but not after HIIT, 4 × 4 min, nor SIT, 10 × 30 s. Long-distance (3000-m) endurance performance increased (p < 0.05-p < 0.001) in all groups (HIIT, 4 × 4 min: 5.9 ± 3.2%; SIT, 8 × 20 s: 4.1 ± 3.7%; SIT, 10 × 30 s: 2.2 ± 2.2%), with HIIT increasing more than SIT, 10 × 30 s (p < 0.05). Sprint (300-m) performance exhibited within-group increases in SIT, 8 × 20 s (4.4 ± 2.0%) and SIT, 10 × 30 s (3.3 ± 2.8%). In conclusion, HIIT improves V̇O2max more than SIT. Given the importance of V̇O2max for most endurance performance scenarios, HIIT should typically be the chosen interval format.

Aerobic high-intensity intervals improve V̇O2max more than supramaximal sprint intervals in females, similar to males.

INTRODUCTION: Maximal oxygen uptake (V̇O2max ) is a pivotal factor for aerobic endurance performance. Recently, aerobic high-intensity interval training (HIIT) was documented to be superior to sprint interval training (SIT) in improving V̇O2max in well-trained males. However, as mounting evidence suggests that physiological responses to training are sex-dependent, examining the effects of HIIT versus SIT on V̇O2max , anaerobic capacity, and endurance performance in females is warranted. METHODS: We randomized 81 aerobically well-trained females (22 ± 2 years, 51.8 ± 3.6 mL∙kg-1 ∙min-1 V̇O2max ), training three times weekly for 8 weeks, to well-established protocols: (1) HIIT 4 × 4 min at ~95% of maximal aerobic speed (MAS), with 3 min active recovery (2) SIT 8 × 20 s at ~150% of MAS, with 10 s passive recovery (3) SIT 10 × 30 s at ~175% of MAS, with 3.5 min active recovery. RESULTS: Only HIIT 4 × 4 min increased V̇O2max (7.3 ± 3.1%), different from both SIT groups (all p < 0.001). Anaerobic capacity (maximal accumulated oxygen deficit) increased following SIT 8 × 20 s (6.5 ± 10.5%, p < 0.05), SIT 10 × 30 s (14.4 ± 13.7%, p < 0.05; different from HIIT 4 × 4 min, p < 0.05). SIT 10 × 30 s resulted in eight training-induced injuries, different from no injuries following HIIT 4 × 4 min and SIT 8 × 20 s (p < 0.001). All groups improved long-distance (3000-meter) and sprint (300-meter) running performance (all p < 0.001). SIT protocols improved sprint performance more than HIIT 4 × 4 min (p < 0.05). Compared to previous male results, no increase in V̇O2max following SIT 8 × 20 s (p < 0.01), and a higher injury rate for SIT 10 × 30 s (p < 0.001), were evident. CONCLUSIONS: In aerobically well-trained women, HIIT is superior to SIT in increasing V̇O2max while all-out treadmill running SIT is potentially more harmful.

Maximal intended velocity enhances strength training-induced neuromuscular stimulation in older adults.

The age-related attenuation in neuromuscular function can be mitigated with strength training. Current recommendations for untrained and elderly recommend performing the strength training with a controlled movement velocity (CON). However, applying maximal intended velocity (MIV) in the concentric phase of movement may augment neuromuscular stimulation and potentially enhance training adaptations. Thus, applying rate of electromyography (EMG) rise (RER) recordings, we examined the acute early phase neuromuscular response to these two contraction types in quadriceps femoris during leg extension, along with actual movement velocity, in 12 older (76 ± 6 years) and 12 young men (23 ± 2 years). Results revealed that older adults had a lower one repetition maximum (1RM) than young (33 ± 9 kg vs. 50 ± 9 kg; p = 0.001) and lower actual velocity across relative intensities of ~ 10%, 30%, 50%, 70% and 90% of 1RM for CON and MIV (all p < 0.05). Older adults also had consistently reduced RER compared to young during both conditions (old: 1043-1810 µV; young: 1844-3015 µV; all p < 0.05). However, RER was higher in contractions with MIV compared to CON for both age groups, and across all intensities (98-674%, all p < 0.05). In conclusion, despite decreased maximal strength and attenuated neuromuscular response with advancing age, our results document an augmented neuromuscular activation when repetitions are performed with MIV in the concentric phase of movement.

Maximal strength training in patients with inflammatory rheumatic disease: implications for physical function and quality of life.

PURPOSE: Patients with inflammatory rheumatic disease (IRD) have attenuated muscle strength in the lower extremities, resulting in impaired physical function and quality of life. Although maximal strength training (MST), applying heavy resistance, is documented to be a potent countermeasure for such attenuation, it is uncertain if it is feasible in IRD given the pain, stiffness, and joint swelling that characterize the population. METHODS: 23 patients with IRD (49 ± 13 years; 20 females/3 males), diagnosed with spondyloarthritis, rheumatoid arthritis, or systemic lupus erythematosus, were randomized to MST or a control group (CG). The MST group performed four × four repetitions dynamic leg press two times per week for 10 weeks at ~ 90% of one repetition maximum (1RM). Before and after training 1RM, rate of force development (RFD), and health-related quality of life (HRQoL) were measured. RESULTS: Session attendance in the MST group was 95%, of which 95% conducted according to MST protocol. Furthermore, MST increased 1RM (29 ± 12%, p = 0.001) and early and late phase RFD (33-76%, p < 0.05). All improvements were different from the CG (p < 0.05). MST also resulted in HRQoL improvements in the dimensions; physical functioning, general health, and vitality (p < 0.05). Physical functioning was associated with 1RM (rho = 0.55, p < 0.01) and early phase RFD (rho = 0.53-0.71, p < 0.01; different from CG p < 0.05). CONCLUSIONS: Despite being characterized by pain, stiffness, and joint swelling, patients with IRD appear to tolerate MST well. Given the improvements in 1RM, RFD, and HRQoL MST should be considered as a treatment strategy to counteract attenuated muscle strength, physical function, and HRQoL. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04998955, retrospectively registered.

Strength training restores force-generating capacity in patients with schizophrenia.

Patients with schizophrenia spectrum disorders have impaired skeletal muscle force-generating capacity (FGC) of the lower extremities, that is, one repetition maximum (1RM) and rapid force development, and poor functional performance. We therefore investigated whether 12 weeks of maximal strength training (MST) could (a) restore FGC and functional performance to the level of healthy references, (b) increase patient activation and quality of life, and (c) explore associations between symptom severity, defined daily dose of medication, illness duration, level of patient activation, and improvements in FGC and functional performance. Forty-eight outpatients were randomized to a training group (TG) or control group (CG). TG performed leg press MST 2 day/week at ~ 90% 1RM. The CG received two introductory training sessions and encouragement to train independently. Leg press 1RM, rapid force development, a battery of functional performance tests, Patient Activation Measure-13, and 36-Item Short Form Health Survey were tested. Healthy references performed baseline tests of FGC and functional performance. Thirty-six patients completed the study (TG: 17, CG: 19). TG improved 1RM (28%) and rapid force development (20%, both P < .01) to a level similar to healthy references, while no change was apparent in the CG. TG's improvement in rapid force development was negatively associated with defined daily dose of medication (r = -0.5, P = .05). Both TG and CG improved 30-second sit-to-stand test performance (P < .05) which was associated with improved rapid force development (r = 0.6, P < .05). In conclusion, 12 weeks of MST restored patients' lower extremity FGC to a level similar to healthy references and improved 30-second sit-to-stand test performance.

Maximal strength training-induced increase in efferent neural drive is not reflected in relative protein expression of SERCA.

INTRODUCTION: Maximal strength training (MST), performed with heavy loads (~ 90% of one repetition maximum; 1RM) and few repetitions, yields large improvements in efferent neural drive, skeletal muscle force production, and skeletal muscle efficiency. However, it is elusive whether neural adaptations following such high intensity strength training may be accompanied by alterations in energy-demanding muscular factors. METHODS: Sixteen healthy young males (24 ± 4 years) were randomized to MST 3 times per week for 8 weeks (n = 8), or a control group (CG; n = 8). Measurements included 1RM and rate of force development (RFD), and evoked potentials recordings (V-wave and H-reflex normalized to M-wave (M) in the soleus muscle) applied to assess efferent neural drive to maximally contracting skeletal muscle. Biopsies were obtained from vastus lateralis and analyzed by western blots and real-time PCR to investigate the relative protein expression and mRNA expression of Sarcoplasmic Reticulum Ca2+ ATPase (SERCA) 1 and SERCA2. RESULTS: Significant improvements in 1RM (17 ± 9%; p < 0.001) and early (0-100 ms), late (0-200 ms) and maximal RFD (31-53%; p < 0.01) were observed after MST, accompanied by increased maximal Vmax/Msup-ratio (9 ± 14%; p = 0.046), with no change in H-reflex to M-wave ratio. No changes were observed in the CG. No pre- to post-training differences were found in mRNA or protein expressions of SERCA1 and SERCA2 in either group. CONCLUSION: MST increased efferent neural drive to maximally contracting skeletal muscle, causing improved force production. No change was observed in SERCA expression, indicating that responses to high intensity strength training may predominantly be governed by neural adaptations.

One-year aerobic interval training in outpatients with schizophrenia: A randomized controlled trial.

Although aerobic interval training (AIT) is recognized to attenuate the risk of cardiovascular disease (CVD) and premature mortality, it appears that it rarely arrives at patients' doorsteps. Thus, this study investigated 1-year effects and feasibility of AIT delivered with adherence support in collaborative care of outpatients with schizophrenia. Forty-eight outpatients (28 men, 35 [31-38] (mean [95% confidence intervals]) years; 20 women, 36 [30-41] years) with schizophrenia spectrum disorders (ICD-10) were randomized to either a collaborative care group provided with municipal transportation service and training supervision (walking/running 4 × 4 minutes at ~90% of peak heart rate; HRpeak ) 2 d wk-1 at the clinic (TG) or a control group (CG) given 2 introductory AIT sessions and advised to continue training. Directly assessed peak oxygen uptake ( V ˙ O 2 peak ) increased in the TG after 3 months (2.3 [0.6-4.4] mL kg-1  min-1 , Cohen's d = 0.33[-4.63 to 4.30], P = 0.04), 6 months (2.7 [0.5-4.8] mL kg-1  min-1 , Cohen's d = 0.42[-4.73 to 4.11], P = 0.02) and 1 year (4.6 [2.3-6.8] mL kg-1  min-1 , Cohen's d = 0.70[-4.31 to 4.10], P < 0.001) compared to the CG. One-year cardiac effects revealed higher HRpeak (7 [2-11] b min-1 , Cohen's d = 0.34[-8.48 to 8.65], P = 0.01), while peak stroke volume tended to be higher (0.9 [-0.2 to 2.0] mL b-1 , Cohen's d = 0.35[-1.62 to 2.01], P = 0.11) in the TG compared to the CG. Conventional risk factors (body weight, waist circumference, blood pressure, and lipids/glucose) remained unaltered in both groups. One-year AIT adherence rates were 15/25 (TG; different from CG: P < 0.001) and 0/23 (CG). AIT was successfully included in long-term collaborative care of outpatients with schizophrenia and yielded improved V ˙ O 2 peak , advocating this model for aerobic capacity improvement and CVD risk reduction in future treatment.

Patients with schizophrenia have impaired muscle force-generating capacity and functional performance.

Patients with schizophrenia have impaired physical health. However, evidence of how skeletal muscle force-generating capacity (FGC), a key component of functional performance, may contribute to the impairment is scarce. Thus, the aim of this study was to investigate the patient groups' skeletal muscle FGC and its association with functional performance. Leg-press FGC was assessed along with a battery of functional performance tests in 48 outpatients (28 men, 34 ± 10 years; 20 women, 36 ± 12 years) with schizophrenia spectrum disorder (ICD-10, F20-29), and compared with 48 healthy age- and gender-matched references. Results revealed reduced one-repetition maximum (1RM) in men (-19%, P < .01) and a trend toward reduction in women (-13%, P = .067). The ability to develop force rapidly was also impaired (men: -30%; women: -25%, both P < .01). Patients scored worse than healthy references on all physical performance tests (stair climbing: -63%; 30-second sit-to-stand (30sSTS): -48%; six-minute walk test (6MWT): -22%; walking efficiency: -14%; and unipedal stance eyes open: -20% and closed: -73%, all P < .01). 1RM correlated with 6MWT (r = .45), stair climbing (r = -.44), 30sSTS (r = .43), walking efficiency (r = .26), and stance eyes open (r = .33) and closed (r = .45), all P < .01. Rapid force development correlated with 6MWT (r = .54), stair climbing (r = -.49), 30sSTS (r = .45), walking efficiency (r = .26), and stance eyes open (r = .44) and closed (r = .51), all P < .01. In conclusion, skeletal muscle FGC and functional performance are reduced in patients with schizophrenia and should be recognized as important aspects of the patient groups' impaired health. Resistance training aiming to improve these components should be considered an important part of clinical treatment.

A comprehensive cardiovascular disease risk profile in patients with schizophrenia.

Patients with schizophrenia are physically inactive and have high prevalence of cardiovascular disease (CVD). Peak oxygen uptake (V̇O2peak ) is one of the strongest predictors for CVD, yet is rarely investigated in this patient population, and how V̇O2peak relates to other conventional CVD risk measures in this population is unclear. We measured treadmill V̇O2peak along with daily physical activity assessed by triaxial accelerometry, body mass index (BMI), waist circumference, blood pressure, lipid profiles, and glucose in 48 outpatients (28 men, 35 ± 10 (SD) years; 20 women, 35 ± 12 years), diagnosed with schizophrenia, schizotypal, or delusional disorders (ICD-10; F20-29). The patients were compared with 48 age- and sex-matched healthy references (±2 years) and normative data from the population. V̇O2peak was 34.5 ± 8.7 mL/kg/min (men) and 26.4 ± 7.0 mL/kg/min (women), which was 27% and 30% lower than healthy references, respectively (both P < 0.01). V̇O2peak was not associated with daily physical activity in men while a weak association was seen in women (steps per day: r2  = 0.26; counts per minute: r2  = 0.25; P < 0.05). BMI (26.0 ± 6.1 kg/m2 ) revealed that patients were moderately overweight with a waist circumference of 103 ± 17 cm. Lipid- and glucose levels, and blood pressure were all within normative range. Our data advocate the utilization of V̇O2peak assessment for CVD risk profile determination in patients with schizophrenia. Daily physical activity was poorly and inconsistently related to V̇O2peak, suggesting increased daily physical activity might not translate into improved V̇O2peak and CVD risk reduction.

Prediction of upper extremity peak oxygen consumption from heart rate during submaximal arm cycling in young and middle-aged adults.

Based on the strong linear relationship between heart rate (HR) and oxygen consumption, the Åstrand-Ryhming cycle ergometer test (Astrand and Ryhming in J Appl Physiol 7:218-221, 1954) is a widely used submaximal test to predict whole body maximal oxygen consumption ([Formula: see text]). However, a similar test predicting peak oxygen consumption ([Formula: see text]) in the upper extremities is not established, and may be very useful for individuals unable to use their lower extremities or/and if separation of upper extremity aerobic capacity is sought after. Thus, the aim of the current study was to develop a submaximal test predicting [Formula: see text] in arm-cycling. Forty-nine healthy volunteers (25 women: 38 ± 13 years; 24 men: 39 ± 12 years) tested arm-cycle [Formula: see text] on a protocol with 4-min, 21-W increments to exhaustion. The data were contrasted to treadmill [Formula: see text] values. Arm-cycle [Formula: see text] was 66 ± 8% of [Formula: see text] (r = 0.92, p < 0.001; women: 1.9 ± 0.4 L min-1; men: 3.0 ± 0.7 L min-1). Arm-cycle HR and [Formula: see text] exhibited correlations of r = 0.79 and r = 0.78 for women and men, respectively, while corresponding correlations between work rate and [Formula: see text] were r = 0.95 (women) and r = 0.89 (men) (all p < 0.001). Arm-cycle [Formula: see text] prediction revealed a standard error of estimate (SEE) of 11.2% (women) and 10.2% (men), and was primarily due to individual arm-cycle maximal HR (women: 173 ± 13 beats min-1; men: 174 ± 10 beats min-1; correction factor: 5-7%). In conclusion, from a single 4-min stage of submaximal arm cycling, [Formula: see text] can be predicted with a SEE of 10-11%. The arm-cycle test may have important value for individuals who rely on arms in sports and occupations, and for patients with lower extremity disabilities.

Fatigue-related group III/IV muscle afferent feedback facilitates intracortical inhibition during locomotor exercise.

KEY POINTS: This study investigated the influence of group III/IV muscle afferents on corticospinal excitability during cycling exercise and focused on GABAB neuron-mediated inhibition as a potential underlying mechanism. The study provides novel evidence to demonstrate that group III/IV muscle afferent feedback facilitates inhibitory intracortical neurons during whole body exercise. Firing of these interneurons probably contributes to the development of central fatigue during physical activity. ABSTRACT: We investigated the influence of group III/IV muscle afferents in determining corticospinal excitability during cycling exercise and focused on GABAB neuron-mediated inhibition as a potential underlying mechanism. Both under control conditions (CTRL) and with lumbar intrathecal fentanyl (FENT) impairing feedback from group III/IV leg muscle afferents, subjects (n = 11) cycled at a comparable vastus-lateralis EMG signal (∼0.26 mV) before (PRE; 100 W) and immediately after (POST; 90 ± 2 W) fatiguing constant-load cycling exercise (80% Wpeak; 221 ± 10 W; ∼8 min). During, PRE and POST cycling, single and paired-pulse (100 ms interstimulus interval) transcranial magnetic stimulations (TMS) were applied to elicit unconditioned and conditioned motor-evoked potentials (MEPs), respectively. To distinguish between cortical and spinal contributions to the MEPs, cervicomedullary stimulations (CMS) were used to elicit unconditioned (CMS only) and conditioned (TMS+CMS, 100 ms interval) cervicomedullary motor-evoked potentials (CMEPs). While unconditioned MEPs were unchanged from PRE to POST in CTRL, unconditioned CMEPs increased significantly, resulting in a decrease in unconditioned MEP/CMEP (P < 0.05). This paralleled a reduction in conditioned MEP (P < 0.05) and no change in conditioned CMEP. During FENT, unconditioned and conditioned MEPs and CMEPs were similar and comparable during PRE and POST (P > 0.2). These findings reveal that feedback from group III/IV muscle afferents innervating locomotor muscle decreases the excitability of the motor cortex during fatiguing cycling exercise. This impairment is, at least in part, determined by the facilitating effect of these sensory neurons on inhibitory GABAB intracortical interneurons.

Maximal strength training: the impact of eccentric overload.

The search for the most potent strength training intervention is continuous. Maximal strength training (MST) yields large improvements in force-generating capacity (FGC), largely attributed to efferent neural drive enhancement. However, it remains elusive whether eccentric overload, before the concentric phase, may augment training-induced neuromuscular adaptations. A total of 53 23 ± 3 (SD)-yr-old untrained males were randomized to either a nontraining control group (CG) or one of two training groups performing leg press strength training with linear progression, three times per week for 8 wk. The first training group carried out MST with four sets of four repetitions at ~90% one-repetition maximum (1RM) in both action phases. The second group performed MST with an augmented eccentric load of 150% 1RM (eMST). Measurements were taken of 1RM and rate of force development (RFD), countermovement jump (CMJ) performance, and evoked potentials recordings [V-wave (V) and H-reflex (H) normalized to M-wave (M) in musculus soleus]. 1RM increased from 133 ± 16 to 157 ± 23 kg and 123 ± 18 to 149 ± 22 kg and CMJ by 2.3 ± 3.6 and 2.2 ± 3.7cm for MST and eMST, respectively (all P < 0.05). Early, late, and maximal RFD increased in both groups [634-1,501 N/s (MST); 644-2,111 N/s (eMST); P < 0.05]. These functional improvements were accompanied by increased V/M-ratio (MST: 0.34 ± 0.11 to 0.42 ± 14; eMST: .36 ± 0.14 to 0.43 ± 13; P < 0.05). Resting H/M-ratio remained unchanged. Training-induced improvements did not differ. All increases, except for CMJ, were different from the CG. MST is an enterprise for large gains in FGC and functional performance. Eccentric overload did not induce additional improvements, suggesting firing frequency and motor unit recruitment during MST may be maximal. NEW & NOTEWORTHY This is the first study to apply evoked potential recordings to investigate effects on efferent neural drive following high-intensity strength training with and without eccentric overload in a functionally relevant lower extremity exercise. We document that eccentric overload does not augment improvements in efferent neural drive or muscle force-generating capacity, suggesting that high-intensity concentric loads may maximally tax firing frequency and motor unit recruitment.

Maximal strength training-induced improvements in forearm work efficiency are associated with reduced blood flow.

Maximal strength training (MST) improves work efficiency. However, since blood flow is greatly dictated by muscle contractions in arms during exercise and vascular conductance is lower, it has been indicated that arms rely more upon adapting oxygen extraction than legs in response to the enhanced work efficiency. Thus, to investigate if metabolic and vascular responses are arm specific, we used Doppler-ultrasound and a catheter placed in the subclavian vein to measure blood flow and the arteriovenous oxygen difference during steady-state work in seven young men [24 ± 3 (SD) yr] following 6 wk of handgrip MST. As expected, MST improved maximal strength (49 ± 9 to 62 ± 10 kg) and the rate of force development (923 ± 224 to 1,086 ± 238 N/s), resulting in a reduced submaximal oxygen uptake (30 ± 9 to 24 ± 10 ml/min) and concomitantly increased work efficiency (9.3 ± 2.5 to 12.4 ± 3.9%) (all P < 0.05). In turn, the work efficiency improvement was associated with reduced blood flow (486 ± 102 to 395 ± 114 ml/min), mediated by a lower blood velocity (43 ± 8 to 32 ± 6 cm/s) (all P < 0.05). Conduit artery diameter and the arteriovenous oxygen difference remained unaltered. The maximal work test revealed an increased time to exhaustion (949 ± 239 to 1,102 ± 292 s) and maximal work rate (both P < 0.05) but no change in peak oxygen uptake. In conclusion, despite prior indications of metabolic and vascular limb-specific differences, these results reveal that improved work efficiency after small muscle mass strength training in the upper extremities is accompanied by a blood flow reduction and coheres with what has been documented for lower extremities. NEW & NOTEWORTHY Maximal strength training increases skeletal muscle work efficiency. Oxygen extraction has been indicated to be the adapting component with this increased work efficiency in arms. However, we document that decreased blood flow, achieved by blood velocity reduction, is the adapting mechanism responding to the improved aerobic metabolism in the forearm musculature.

Increased Blood Lactate Level Deteriorates Running Economy in World Class Endurance Athletes.

Blood lactate accumulation is associated with development of muscle fatigue and negatively correlated to endurance performance. No research has quantified the effects of lactate presence at moderate levels of lactate accumulation. The purpose of this study was to test whether 2 moderate blood lactate concentration levels affect running economy (RE) when running at the individual lactate threshold (LT). Seven male world class endurance athletes with an average V[Combining Dot Above]O2max of 80.7 ± 2.7 ml·kg·min or 5.8 ± 0.5 L·min participated in this study. After the V[Combining Dot Above]O2max test, the subjects were resting or walking and in a random order tested for RE at their LT velocity when the blood lactate level reached either 3 mmol·L or 5 mmol·L. After a new 5-minute exercising period at maximal aerobic velocity, the crossover lactate value RE testing was performed. Running economy was significantly (p ≤ 0.05) deteriorated from 0.668 ± 0.044 to 0.705 ± 0.056 ml·kg·m or 5.5% (p ≤ 0.05) for blood lactate level of 3 mmol·L compared with 5 mmol·L, respectively. Increased lactate level from 3 to 5 mmol·L is thus accompanied by deteriorated RE at LT running velocity. The deteriorated RE at moderate levels of lactate concentration emphasizes the importance of avoiding intensities above LT in the early parts of a dominantly aerobic endurance competition. It also emphasizes the importance of a high V[Combining Dot Above]O2max for aerobic endurance athletes and may partly explain the V[Combining Dot Above]O2 slow component as impaired RE.

Aerobic high-intensity interval training and maximal strength training in patients with unspecific musculoskeletal disorders improve V̇O2peak and maximal strength more than moderate training.

Improving peak oxygen uptake (V̇O2peak) and maximal strength are key objectives of rehabilitation for patients with unspecific musculoskeletal disorders (MSDs). Although high-intensity training yield superior outcomes for these factors, patients with MSDs may not tolerate high-intensity due to pain and fear. Therefore, we examined the effect and feasibility of incorporating aerobic high-intensity intervals (HIITs) and maximal strength training (MST) in a standard clinical rehabilitation program for patients with unspecific MSDs. 73 patients (45 ± 10 years) with MSDs partaking in a standard, public, and 4-week rehabilitation program were randomized to high-intensity training (HG: 4 × 4 minutes intervals at ∼90% of maximal heart rate; HRmax, and 4 × 4 repetitions leg press at ∼90% of 1 repetition maximum; 1RM, with maximal intended velocity) or keep todays treatment of low-to moderate-intensity training (MG: various cycling, walking, and/or running activities at ∼70%-80% of HRmax and 3 × 8 - 10 repetitions leg press at ∼75% of 1RM without maximal intended velocity). HG improved V̇O2peak (12 ± 7%) and leg press 1RM (43 ± 34%) more than moderate-intensity group (V̇O2peak; 5 ± 6%, 1RM; 19 ± 18%, both p < 0.001). We observed that no adverse events and no between-group differences in dropout rate or self-reported quality of life (both p > 0.05). There were positive correlations between improved V̇O2peak and improved physical (p = 0.024) and emotional (0.016) role functioning. We conclude that both high-intensity interval training and MST are feasible and improve V̇O2peak and maximal strength more than standard low-to moderate-intensity treatment of patients with unspecific MSDs. Our findings suggest that high-intensity training should be implemented as a part of standard clinical care of this patient population.

Everyday function in schizophrenia: The impact of aerobic endurance and skeletal muscle strength.

BACKGROUND: Patients with schizophrenia suffer from physical health conditions, culminating in reduced physical functioning with enormous costs for patients and society. Although aerobic endurance and skeletal muscle strength, typically reduced in this population, relate to cognition and function, no study has explored their respective contributions to performance of functional skills and everyday tasks. METHODS: In a cross-sectional study, 48 outpatients (28/20 men/women; 35 ± 11(SD) years) with schizophrenia spectrum disorders (ICD-10; F20-25) were administered the UCSD Performance-based Skills Assessment-Brief (UPSA-B; functional skills), Specific Level of Functioning (SLOF; functional performance) and the Positive and Negative Syndrome (PANSS) scale. Peak oxygen uptake (V̇O2peak) was assessed along with leg press maximal muscle strength (1RM) and mechanical power. RESULTS: UPSA-B performance was associated with V̇O2peak (r = 0.28,p < 0.05), accounting for 8 % (p < 0.05) of shared variance, but was unrelated to 1RM and mechanical power. The SLOF physical functioning domain was associated with V̇O2peak (r = 0.30,p < 0.05) and 1RM (r = 0.24,p < 0.05), while SLOF personal care (r = 0.27,p < 0.05) and activities (r = 0.30,p < 0.05) were related only to V̇O2peak. Hierarchical regression analyses revealed that while V̇O2peak and age combined to account for 20 % (p < 0.05) of the variance in physical functioning, the contribution of 1RM was eliminated after adjusting for age. V̇O2peak and negative symptoms combined predicted 24 % and 35 % of the variance in personal care and activities, respectively. UPSA-B scores did not add to the prediction of SLOF scores. CONCLUSIONS: Although V̇O2peak and 1RM both relate to functional outcomes, the combination of V̇O2peak, age, and negative symptoms exert the greatest detrimental influence on functional performance beyond skills deficits.

Aging increases metabolic capacity and reduces work efficiency during handgrip exercise in males.

Maximal oxygen uptake and exercise performance typically decline with age. However, there are indications of preserved vascular function and blood flow regulation during arm exercise. Yet, it is unknown if this potential physiological preservation with age is mirrored in peripheral metabolic capacity and V̇o2/W ratio. Thus, to investigate the effects of aging in the arms, we measured metabolic and vascular responses to 6-min bouts of dynamic handgrip exercise at 40% and 80% of maximal work rate (WRmax) in 11 young (26 ± 2 yr) and 12 old (80 ± 6 yr) males, applying Doppler-ultrasound combined with blood samples from a deep forearm vein. At baseline, the old had a larger arterial diameter compared with young (P < 0.001). During exercise, the two groups reached the same WRmax. V̇o2, blood flow, and oxygen supply were higher (40%WRmax; 80%WRmax, all P < 0.01), and arteriovenous oxygen difference was lower (80%WRmax, P < 0.02), in old compared with young. Old also had a higher oxygen excess at 80%WRmax (P < 0.01) than young, whereas no difference in muscle diffusion or oxygen extraction was detected. Only young exhibited an increase in intensity-induced arterial dilation (P < 0.05), and they had a lower mean arterial pressure than old at 80%WRmax (P < 0.001). V̇o2/W (40%WRmax; 80%WRmax) was reduced in old compared with young (both P < 0.05). In conclusion, in old and young males with a similar handgrip WRmax, old had a higher V̇o2 during 80%WRmax intensity, achieved by an increased blood flow. This may be a result of the available cardiac output reserve, compensating for reduced work efficiency and attenuated vascular response observed in old.NEW & NOTEWORTHY Contrasting the typically observed decline in V̇o2max with age, the current study reveals an age-related increase in forearm metabolic capacity during handgrip exercise in old, mediated by an increased forearm blood flow. Exercise with a small muscle mass in arms, where central components of the oxygen transport are not limiting, allows old to attain a similar maximal work rate as young despite their increased V̇o2/W ratio.

Strength versus endurance trained master athletes: Contrasting neurophysiological adaptations.

Neural factors play a critical role in the age-related decline in maximal strength and rate of force development (RFD). However, it is uncertain how the age-related attenuation in neuromuscular function may be mitigated in strength or endurance trained master athletes. In this study we applied evoked spinal motoneuron recordings to examine descending motor drive, i.e., efferent drive from supraspinal and spinal centres during maximal voluntary contraction (MVC; V-wave) and H-reflex excitability measured at 10 % MVC in older (>65 yrs) and younger (<35 yrs) strength athletes (n = 21), endurance athletes (n = 17) and untrained control participants (n = 30). Both strength (b = 0.09 [0.01-0.18], p = 0.038) and endurance training (b = 0.14 [0.04-0.23], p = 0.006) were associated with a high V-wave amplitude. This was likely explained by an elevated H-reflex excitability (b = 0.23 [0.11-0.35], p < 0.001) in endurance trained participants, which failed to be seen in strength trained participants. These contrasting neurophysiological properties were accompanied by different physiological traits; strength training was associated with high maximal strength (b = 107.5 [84.6 to 130.4] kg, p < 0.001) and RFD (b = 3171 [2248 to 4094] N‧s-1, p < 0.001), whereas endurance training was associated with elevated maximal oxygen uptake (V̇O2max; b = 13.6 [8.0-19.2] ml‧kg-1‧min-1, p < 0.001). This pattern was apparent irrespective of age, although all traits were negatively associated with advanced age (p < 0.05). In conclusion, strength trained individuals demonstrate higher descending motor drive (elevated V-wave responses), compared to age-matched untrained individuals. Endurance trained individuals also showed elevated V-wave responses, uniquely accompanied by enhanced α-motoneuron excitability and/or reduced pre/postsynaptic inhibition (elevated H-reflex responses). Since a high descending motor drive is a key component of strong muscle contractions, strength training should be emphasized to sustain the ability to carry out force-dependent tasks at older age.

Abdominal aerobic endurance exercise reveals spot reduction exists: A randomized controlled trial.

The existence of spot reduction, exercise-induced local body fat reduction, has been debated for half a century. Although the evidence is equivocal, no study has applied aerobic endurance training closely matching interventions for energy expenditure. Sixteen overweight (BMI: 29.8 ± 3.3(SD) kg m-2 ) males (43 ± 9 years) were randomized to: (1) abdominal endurance exercise (AG), combining treadmill running at 70% HRmax (27 min) with 4 × 4 min (30%-40% maximal strength, 1RM) of torso rotation and abdominal crunches (57 min), 4 days⋅week-1 for 10 weeks; or (2) control group (CG) performing only treadmill running (45 min) at 70% HRmax . Local fat mass was measured by dual-energy x-ray absorptiometry (DEXA), along with 1RM, and pulmonary oxygen uptake (to control energy expenditure during training). Trunk fat mass decreased more (697 g, 3%, p < 0.05) in AG (1170 ± 1093 g, 7%; p < 0.05) than in CG (no change). Total fat mass (AG: 1705 ± 1179 g, 6%; CG: 1134 ± 731 g, 5%; both p < 0.01) and body weight (AG: 1.2 ± 1.2 kg, 1%, p < 0.05; CG: 2.3 ± 0.9 kg, 3%, p < 0.01) decreased similarly in AG/CG. Torso rotation (AG: 32 ± 16 kg, 39%, p < 0.01; CG: no change) and abdominal crunch 1RM (AG: 35 ± 16 kg, 36%, p < 0.01; CG: 13 ± 12 kg, 17%, p < 0.05) increased more (p < 0.05/0.01) in AG than CG. Abdominal endurance exercise utilized more local fat than treadmill running, indicating that spot reduction exists in adult males.