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.

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.

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.

Prediction of VO2max From Submaximal Exercise Using the Smartphone Application Myworkout GO: Validation Study of a Digital Health Method.

BACKGROUND: Physical inactivity remains the largest risk factor for the development of cardiovascular disease worldwide. Wearable devices have become a popular method of measuring activity-based outcomes and facilitating behavior change to increase cardiorespiratory fitness (CRF) or maximal oxygen consumption (VO2max) and reduce weight. However, it is critical to determine their accuracy in measuring these variables. OBJECTIVE: This study aimed to determine the accuracy of using a smartphone and the application Myworkout GO for submaximal prediction of VO2max. METHODS: Participants included 162 healthy volunteers: 58 women and 104 men (17-73 years old). The study consisted of 3 experimental tests randomized to 3 separate days. One-day VO2max was assessed with Metamax II, with the participant walking or running on the treadmill. On the 2 other days, the application Myworkout GO used standardized high aerobic intensity interval training (HIIT) on the treadmill to predict VO2max. RESULTS: There were no significant differences between directly measured VO2max (mean 49, SD 14 mL/kg/min) compared with the VO2max predicted by Myworkout GO (mean 50, SD 14 mL/kg/min). The direct and predicted VO2max values were highly correlated, with an R2 of 0.97 (P<.001) and standard error of the estimate (SEE) of 2.2 mL/kg/min, with no sex differences. CONCLUSIONS: Myworkout GO accurately calculated VO2max, with an SEE of 4.5% in the total group. The submaximal HIIT session (4 x 4 minutes) incorporated in the application was tolerated well by the participants. We present health care providers and their patients with a more accurate and practical version of health risk estimation. This might increase physical activity and improve exercise habits in the general population.

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.

Smartphone-Assisted High-Intensity Interval Training in Inflammatory Rheumatic Disease Patients: Randomized Controlled Trial.

BACKGROUND: Patients with inflammatory rheumatic diseases (IRDs) experience disease-related barriers to physical training. Compared with the general population, IRD patients are reported to have reduced maximal oxygen uptake (VO2max) and physical activity levels. Supervised high-intensity interval training (HIIT) is documented to counteract the reduced VO2max and poor cardiovascular health associated with IRDs. However, supervised HIIT is resource demanding. OBJECTIVE: This study sought to investigate if self-administered 4×4-min HIIT guided by a smartphone app (Myworkout GO) could yield similar HIIT-induced effects as standard 4×4-min HIIT performed under the guidance and supervision of health care professionals. The effects studied were on VO2max and health-related quality of life (HRQoL). METHODS: Forty patients (33 female patients, mean age 48 years, SD 12 years; 7 male patients, mean age 52 years, SD 11 years) diagnosed with rheumatoid arthritis, spondyloarthritis, or systemic lupus erythematosus were randomized to a supervised group (SG) or an app group (AG). Both groups were instructed to perform 4×4-min intervals with a rate of perceived exertion of 16 to 17, corresponding to 85% to 95% of the maximal heart rate, twice a week for 10 weeks. Treadmill VO2max and HRQoL measured using RAND-36 were assessed before and after the exercise period. RESULTS: VO2max increased (P<.001) in both groups after 10 weeks of HIIT, with improvements of 3.6 (SD 1.3) mL/kg/min in the SG and 3.7 (SD 1.5) mL/kg/min in the AG. This was accompanied by increases in oxygen pulse in both groups (P<.001), with no between-group differences apparent for either measure. Improvements in the HRQoL dimensions of bodily pain, vitality, and social functioning were observed for both groups (P<.001 to P=.04). Again, no between-group differences were detected. CONCLUSIONS: High-intensity 4×4-min interval training increased VO2max and HRQoL, contributing to patients' reduced cardiovascular disease risk, improved health and performance, and enhanced quality of life. Similar improvements were observed following HIIT when IRD patients were guided using perceived exertion by health care professionals or the training was self-administered and guided by the app Myworkout GO. Utilization of the app may help reduce the cost of HIIT as a treatment strategy in this patient population. TRIAL REGISTRATION: ClinicalTrials.gov NCT04649528; https://clinicaltrials.gov/ct2/show/NCT04649528.

Early Maximal Strength Training Improves Leg Strength and Postural Stability in Elderly Following Hip Fracture Surgery.

INTRODUCTION: Hip fractures predominantly occur in the geriatric population and results in increased physical inactivity and reduced independency, largely influenced by a downward spiral of ambulatory capacity, related to loss of skeletal muscle strength and postural stability. Thus, effective postoperative treatment, targeting improvements in muscle strength, is sought after. MATERIALS & METHODS: Twenty-one hip fracture patients (>65 yr) were randomized to 8 weeks of either conventional physiotherapy control group (CG), or leg press and hip abduction maximal strength training (MST) 3 times per week. MST was performed applying heavy loads (85-90% of 1 repetition maximum; 1RM) and 4-5 repetitions in 4 sets. Maximal strength (bi- and unilateral 1RM), postural stability (unipedal stance test; UPS), and DEXA-scan bone mineral content/ density (BMC/BMD) were measured before and after the 8-week rehabilitation. RESULTS: Both MST and conventional physiotherapy improved bilateral leg press 1RM by 41 ± 27 kg and 29 ± 17 kg, respectively (both p < 0.01), while unilateral leg press 1RM only increased after MST (within group and between groups difference: both p < 0.05). MST also resulted in an increase in abduction 1RM in both the fractured (5 kg, 95%CI: 2-7; p < 0.01) and healthy limb (6 kg, 95%CI: 3-9; p < 0.01), while no such improvement was apparent in the CG (between groups difference: p < 0.01). Finally, MST improved UPS of the fractured limb (p < 0.05). No differences were observed in BMC or BMD following the 8 weeks. DISCUSSION: Early postoperative MST improved lower extremities maximal muscle strength more than conventional physiotherapy and was accompanied by improvements in postural stability. CONCLUSION: Implementing MST in early rehabilitation after hip fracture surgery should be considered as a relevant treatment to curtail the downward spiral of reduced ambulatory capacity typical for this patient group, possibly reducing the risk of recuring falls and excess mortality. TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT03030092.

High-Intensity Shoulder Abduction Exercise in Subacromial Pain Syndrome.

Subacromial pain syndrome (SAPS) defined as pain of nontraumatic origin localized around the acromion, is a debilitating, common, and often chronic condition. Among many proposed underlying causes of SAPS, hypoperfusion and hypoxic conditions in and around the tendons may be an intrinsic cause of SAPS. PURPOSE: This study aimed to determine if adding high-intensity aerobic interval training (HIIT) of the rotator cuff to usual care was feasible in SAPS and improved shoulder endurance more than usual care alone, as well as to examine the influence on shoulder pain and disability and the response of tendinous microcirculation after HIIT. METHODS: Twenty-one subjects with chronic SAPS were randomized to two groups: experimental group (EG; n = 13) receiving HIIT in addition to treatment as usual and control group (CG; n = 8) receiving treatment as usual. Before and after 8 wk of exercise therapy, endurance performance was assessed by an incremental abduction exercise of the arm to exhaustion (TTE). Pain and disability was assessed by the shoulder pain and disability index (SPADI). Contrast-enhanced ultrasound of the musculus supraspinatus and tendon was utilized to indicate tendon blood flow. RESULTS: Endurance in the TTE test improved by an estimated 233 s more on average in EG than in CG (P = 0.001; 95% confidence interval, 102 to 363). The SPADI score was reduced 22 points more on average in EG (P = 0.017; 95% confidence interval, -40 to -5). The change from pretest to posttest was significant in EG for both TTE test and SPADI improvement (P < 0.001). EG also experienced less pain during exercise after the intervention compared with CG (P < 0.001). Contrast-enhanced ultrasound indicated an increase in tendinous blood flow in EG (P = 0.019). CONCLUSIONS: HIIT rotator cuff exercise seems to be a feasible intervention in SAPS, increasing endurance performance more than usual care alone.

Determinants of the diminished exercise capacity in patients with chronic obstructive pulmonary disease: looking beyond the lungs.

KEY POINTS: Peak oxygen uptake, a primary determinant of prognosis, mortality and quality of life, is diminished in patients with chronic obstructive pulmonary disease (COPD), with mounting evidence supporting an important role for peripheral dysfunction, particularly within skeletal muscle. In patients with severe COPD and activity-matched controls, muscle oxygen transport and utilization were assessed at peak effort during single-leg knee-extensor exercise (KE), where ventilation is assumed to be submaximal. This strategy removes ventilation as the major constraint to exercise capacity in COPD, allowing maximal muscle function to be attained and evaluated. During maximal KE, both convective arterial oxygen delivery to the skeletal muscle microvasculature and subsequent diffusive oxygen delivery to the mitochondria were diminished in patients with COPD compared to control subjects. These findings emphasize the importance of factors, beyond the lungs, that influence exercise capacity in this patient population and may, ultimately, influence the prognosis, mortality and quality of life for patients with COPD. ABSTRACT: Peak oxygen uptake ( V̇O2peak ), a primary determinant of prognosis, mortality and quality of life, is diminished in patients with chronic obstructive pulmonary disease (COPD). Mounting evidence supports an important role of the periphery, particularly skeletal muscle, in the diminished V̇O2peak with COPD. However, the peripheral determinants of V̇O2peak have not been comprehensively assessed in this cohort. Thus, the hypothesis was tested that both muscle convective and diffusive oxygen (O2 ) transport, and therefore skeletal muscle peak O2 uptake ( V̇MO2peak ), are diminished in patients with COPD compared to matched healthy controls, even when ventilatory limitations (i.e. attainment of maximal ventilation) are minimized by using small muscle mass exercise. Muscle O2 transport and utilization were assessed at peak exercise from femoral arterial and venous blood samples and leg blood flow (by thermodilution) in eight patients with severe COPD (forced expiratory volume in 1s (FEV1 ) ± SEM = 0.9 ± 0.1 l, 30% of predicted) and eight controls during single-leg knee-extensor exercise. Both muscle convective O2 delivery (0.44 ± 0.06 vs. 0.69 ± 0.07 l min-1 , P < 0.05) and muscle diffusive O2 conductance (6.6 ± 0.8 vs. 10.4 ± 0.9 ml min-1  mmHg-1 , P < 0.05) were ∼1/3 lower in patients with COPD than controls, resulting in an attenuated V̇MO2peak in the patients (0.27 ± 0.04 vs. 0.42 ± 0.05 l min-1 , P < 0.05). When cardiopulmonary limitations to exercise are minimized, the convective and diffusive determinants of V̇MO2peak , at the level of the skeletal muscle, are greatly attenuated in patients with COPD. These findings emphasize the importance of factors, beyond the lungs, that may ultimately influence this population's prognosis, mortality and quality of life.

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.

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

BACKGROUND AND PURPOSE: 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. METHODS: 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. RESULTS: 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%). CONCLUSION: 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.

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.

Arm Cycling Combined with Passive Leg Cycling Enhances VO2peak in Persons with Spinal Cord Injury Above the Sixth Thoracic Vertebra.

Objective: To test whether passive leg cycling (PLC) during arm cycling ergometry (ACE) affects peak oxygen uptake (VO2peak) differently in individuals with spinal cord injury (SCI) at/above the 6th thoracic vertebra (T6) and below T6. Methods: We conducted a cross-sectional study, analyzed by univariate and multivariate regression models. Between- and within-group differences were examined during (a) ACE only, (b) ACE combined with PLC (ACE-PLC), and (c) ACE combined with functional electrical stimulation cycling (FES hybrid). Fifteen SCI subjects were recruited and grouped according to injury level: at/above T6 (SCI-high, n = 8) or below T6 (SCI-low, n = 7). VO2peak tests during ACE only, ACE-PLC, and FES hybrid were performed in random order on separate days. Results: In the SCI-high group, mean (SD) VO2peak was 19% higher during ACE-PLC than during ACE only [21.0 (3.8) vs 17.7 (5.0) mL·kg-1·min-1; p = .002], while VO2peak during FES hybrid cycling was 16% higher than during ACE-PLC [24.4 (4.1) mL·kg-1·min-1; p = .001]. No significant differences among exercise modalities were found for the SCI-low group. Conclusion: Additional training modalities (eg, PLC) during ACE facilitate exercise in SCI-high individuals, but not to the level of the FES hybrid method. Conversely, additional training modalities may not increase training load in SCI-low individuals.

Neural Plasticity with Age: Unilateral Maximal Strength Training Augments Efferent Neural Drive to the Contralateral Limb in Older Adults.

Efferent neural drive during strong muscle contractions is attenuated with age, even after life-long strength training. However, it is unknown if this deterioration may impede contralateral neural plasticity, and limit the clinical value of unilateral strength training. We assessed muscle force-generating capacity, evoked potentials recordings (V-wave and H-reflex normalized to M-wave; V/M-ratio and H/M-ratio) and voluntary activation (VA) in the plantar flexors of the contralateral limb following unilateral maximal strength training (MST) with the dominant limb for 3 weeks (nine sessions). Twenty-three 73 ± 4(SD) year old males were randomized to a MST group (N = 11), exercising with an intensity of ~90% of maximal strength, or a control group (CG, N = 12). MST improved contralateral maximal strength (107.6 ± 27.0 to 119.1 ± 34.8 Nm; 10%) and rate of force development (197.3 ± 54.1 to 232.8 ± 77.7 Nm s-1; 18%) (both p < .05). These strength gains were associated with (r = 0.465-0.608) an enhanced soleus V/M-ratio (0.12 ± 0.09 to 0.21 ± 0.17) and VA (79.5 ± 5.1 to 83.3 ± 5.2%) (all p < .05). H/M-ratio (10% maximal strength) remained unaltered after MST, and no changes were apparent in the CG. In conclusion, cross-limb effects in older adults are regulated by efferent neural drive enhancement, and advocate the clinical relevance of MST to improve neuromuscular function in individuals with conditions that results in unilateral strength reductions.

Impact of maximal strength training on work efficiency and muscle fiber type in the elderly: Implications for physical function and fall prevention.

Although aging is typically associated with a decreased efficiency of locomotion, somewhat surprisingly, there is also a reduction in the proportion of less efficient fast-twitch Type II skeletal muscle fibers and subsequently a greater propensity for falls. Maximal strength training (MST), with an emphasis on velocity in the concentric phase, improves maximal strength, the rate of force development (RFD), and work efficiency, but the impact on muscle morphology in the elderly is unknown. Therefore we evaluated force production, walking work efficiency, and muscle morphology in 11 old (72±3years) subjects before and after MST of the legs. Additionally, for reference, the MST-induced morphometric changes were compared with 7 old (74±6years) subjects who performed conventional strength training (CST), with focus on hypertrophy, as well as 13 young (24±2years) controls. As expected, MST in the old improved maximal strength (68%), RFD (48%), and work efficiency (12%), restoring each to a level similar to the young. However, of importance, these MST-induced functional changes were accompanied by a significant increase in the size (66%) and shift toward a larger percentage (56%) of Type II skeletal muscle fibers, mirroring the adaptations in the hypertrophy trained old subjects, with muscle composition now being similar to the young. In conclusion, MST can increase both work efficiency and Type II skeletal muscle fiber size and percentage in the elderly, supporting the potential role of MST as a countermeasure to maintain both physical function and fall prevention in this population.

The Effect of Age on the V˙O2max Response to High-Intensity Interval Training.

PURPOSE: High-intensity interval training (HIIT) is documented to yield effective improvements in the cardiovascular system and be an excellent strategy for healthy aging. However, it is not determined how age may affect the training response of key components of aerobic endurance. METHODS: We recruited 72 males (mean ± SD, weight = 84.9 ± 12.9 kg, height = 180.4 ± 5.8 cm) and 22 females (weight = 76.0 ± 17.2 kg, height = 171.2 ± 6.7 cm) from 20 to 70+ yr with a training status typical for their age group and divided them into six decade cohorts. The participants followed supervised training with a targeted intensity of 90%-95% of maximal HR (HRmax) three times a week for 8 wk. RESULTS: After HIIT, all age groups increased (P < 0.001-P = 0.004) maximal oxygen consumption (V˙O2max) with 0.39 ± 0.20 (20-29 yr), 0.28 ± 0.21 (30-39 yr), 0.36 ± 0.08 (40-49 yr), 0.34 ± 0.27 (50-59 yr), 0.33 ± 0.23 (60-69 yr), and 0.34 ± 0.14 (70+ yr) L·min, respectively. These 9%-13% improvements were not significantly different between the age groups. In contrast to age, the percentage improvements after HIIT were inversely associated with baseline training status (r = 0.66, P < 0.001). HRmax was not altered within the respective age cohorts, but the two oldest cohorts exhibited a tendency (P = 0.07) to increase HRmax in contrast to a training-induced decrease in the younger cohorts. CONCLUSION: In healthy individuals with an aerobic capacity typical for what is observed in the population, the training response is likely not affected by age in a short-term training intervention but may rather be affected by the initial training status. These findings imply that individuals across age all have a great potential for cardiovascular improvements, and that HIIT may be used as an excellent strategy for healthy aging.

Lifelong strength training mitigates the age-related decline in efferent drive.

Recently, we documented age-related attenuation of efferent drive to contracting skeletal muscle. It remains elusive if this indication of reduced muscle strength is present with lifelong strength training. For this purpose, we examined evoked potentials in the calf muscles of 11 [71 ± 4 (SD) yr] strength-trained master athletes (MA) contrasted with 10 (71 ± 4 yr) sedentary (SO) and 11 (73 ± 6 yr) recreationally active (AO) old subjects, as well as 9 (22 ± 2 yr) young controls. As expected, MA had higher leg press maximal strength (MA, 185 ± 32 kg; AO, 128 ± 15 kg; SO, 106 ± 11 kg; young, 147 ± 22 kg, P < 0.01) and rate of force development (MA, 5,588 ± 2,488 N/s; AO, 2,156 ± 1,100 N/s; SO, 2,011 ± 825 N/s; young, 3,663 ± 1,140 N/s, P < 0.05) than the other groups. MA also exhibited higher musculus soleus normalized V waves during maximal voluntary contractions (MVC) [maximal V wave amplitude/maximal M wave during MVC (Vsup/Msup); 0.28 ± 0.15] than AO (0.13 ± 0.06, P < 0.01) and SO (0.11 ± 0.05, P < 0.01), yet lower than young (0.45 ± 0.12, P < 0.01). No differences were apparent between the old groups in H reflex recorded at rest or during MVC [maximal H reflex amplitude/maximal M wave during rest (Hmax/Mmax); maximal H reflex amplitude during MVC/maximal M wave during MVC (Hsup/Msup)], and all were lower (P < 0.01) than young. MA (34.4 ± 2.1 ms) had shorter (P < 0.05) H reflex latency compared with AO (36.4 ± 3.7 ms) and SO (37.3 ± 3.2 ms), but longer (P < 0.01) than young (30.7 ± 2.0 ms). Using interpolated twitch analysis, MA (89 ± 7%) had plantar flexion voluntary activation similar to young (90 ± 6%), and this was higher (P < 0.05), or tended to be higher (P = 0.06-0.09), than SO (83 ± 10%) and AO (84 ± 5%). These observations suggest that lifelong strength training has a protective effect against age-related attenuation of efferent drive. In contrast, no beneficial effect seems to derive from habitual recreational activity, indicating that strength training may be particularly beneficial for counteracting age-related loss of neuromuscular function.

Arm Crank and Wheelchair Ergometry Produce Similar Peak Oxygen Uptake but Different Work Economy Values in Individuals with Spinal Cord Injury.

Objective. To study whether values for peak oxygen uptake (VO2peak) and work economy (WE) at a standardized workload are different when tested by arm crank ergometry (ACE) and wheelchair ergometry (WCE). Methods. Twelve paraplegic men with spinal cord injury (SCI) in stable neurological condition participated in this cross-sectional repeated-measures study. We determined VO2peak and peak power output (POpeak) values during ACE and WCE in a work-matched protocol. Work economy was tested at a standardized workload of 30 Watts (W) for both ACE and WCE. Results. There were no significant differences in VO2peak (mL·kg(-1)·min(-1)) between ACE (27.3 ± 3.2) and WCE (27.4 ± 3.8) trials, and a Bland-Altman plot shows that findings are within 95% level of agreement. WE or oxygen consumption at 30 W (VO2-30W) was significantly lower during WCE compared to ACE (P < 0.039). Mean (95% CI) POpeak (W) were 130 (111-138) and 100 (83-110) during ACE and WCE, respectively. Conclusion. The findings in the present study support the use of both ACE and WCE for testing peak oxygen uptake. However, WE differed between the two test modalities, meaning that less total energy is used to perform external work of 30 W during wheelchair exercise when using this WCE (VP100 Handisport ergometer). Clinical Trials Protocol Record is NCT00987155/4.2007.2271.

Maximal strength training as physical rehabilitation for patients with substance use disorder; a randomized controlled trial.

BACKGROUND: Patients with substance use disorder (SUD) suffer from multiple health and psychosocial problems. Because poor physical capacities following an inactive lifestyle may indeed contribute to these problems, physical training is often suggested as an attractive supplement to conventional SUD treatment. Strength training is shown to increase muscle strength and effectively improve health and longevity. Therefore we investigated the feasibility and effect of a maximal strength training intervention for SUD patients in clinical treatment. METHODS: 16 males and 8 females were randomized into a training group (TG) and a control group (CG). The TG performed lower extremities maximal strength training (85-90 % of 1 repetition maximum (1RM)) 3 times a week for 8 weeks, while the CG participated in conventional clinical activities. RESULTS: The TG increased hack squat 1RM (88 ± 54 %), plantar flexion 1RM (26 ± 20 %), hack squat rate of force development (82 ± 29 %) and peak force (11 ± 5 %). Additionally, the TG improved neural function, expressed as voluntary V-wave (88 ± 83 %). The CG displayed no change in any physical parameters. The TG also reduced anxiety and insomnia, while the CG reduced anxiety. CONCLUSION: Maximal strength training was feasible for SUD patients in treatment, and improved multiple risk factors for falls, fractures and lifestyle related diseases. As conventional treatment appears to have no effect on muscle strength, systematic strength training should be implemented as part of clinical practice. TRIAL REGESTRATION: ClinicalTrials.gov Identifier: NCT02218970 (August 14, 2014).

The Effect of Physical Activity on Passive Leg Movement-Induced Vasodilation with Age.

INTRODUCTION: Because of reduced nitric oxide (NO) bioavailability with age, passive leg movement (PLM)-induced vasodilation is attenuated in older sedentary subjects and, unlike the young subjects, cannot be augmented by posture-induced elevations in femoral perfusion pressure. However, whether vasodilator function assessed with PLM, and therefore NO bioavailability, is preserved in older individuals with greater physical activity and fitness is unknown. METHODS: PLM was performed on four subject groups: young sedentary (Y, 23 ± 1 yr, n = 12), old sedentary (OS, 73 ± 2 yr, n = 12), old active (OA, 71 ± 2 yr, n = 10), and old endurance trained (OT, 72 ± 1 yr, n = 10) in the supine and upright-seated posture. Hemodynamics were measured using ultrasound Doppler and finger photoplethysmography. RESULTS: In the supine posture, PLM-induced peak change in leg vascular conductance was significantly attenuated in the OS compared with the young subjects (OS = 4.9 ± 0.5, Y = 6.9 ± 0.7 mL·min·mm Hg) but was not different from the young in the OA and OT (OA = 5.9 ± 1.0, OT = 5.4 ± 0.4 mL·min·mm Hg). The upright-seated posture significantly augmented peak change in leg vascular conductance in all but the OS (OS = 4.9 ± 0.5, Y = 11.8 ± 1.3, OA = 7.3 ± 0.8, OT = 8.1 ± 0.8 mL·min·mm Hg), revealing a significant vasodilatory reserve capacity in the other groups (Y = 4.92 ± 1.18, OA = 1.37 ± 0.55, OT = 2.76 ± 0.95 mL·min·mm Hg). CONCLUSIONS: As PLM predominantly reflects NO-mediated vasodilation, these findings support the idea that augmenting physical activity and fitness can protect NO bioavailability, attenuating the deleterious effects of advancing age on vascular function.