Maximal Strength Training Restores Walking Mechanical Effeciency in Heart Patients

Physical Health Impairment and Exercise as Medicine in Severe Mental Disorders: A Narrative Review

BACKGROUND

Individuals with severe mental disorders (SMDs; schizophrenia spectrum disorders, bipolar disorder, and major depressive disorder) are not only suffering from their mental conditions; they also have an attenuated physical health, augmenting their overall critical condition.

OBJECTIVES

We review and critically appraise the evidence based on (1) key physiological factors relating to aerobic endurance and skeletal muscle strength; (2) implications for physical function and health; and (3) effects of training interventions with different intensities evaluated in individuals with SMDs.

FINDINGS

Reductions in aerobic endurance factors, peak oxygen uptake (VO_2peak) and walking work efficiency, are paralleled by reductions in maximal skeletal muscle strength and power. In turn, the poor aerobic endurance and muscle strength lead to impaired physical function, increased risk of lifestyle-related diseases, and ultimately early death. Exercise has the potential to counteract the attenuated physical health in people with SMDs. While aerobic endurance training is shown to increase VO_2peak due to plasticity of the oxygen transport system, strength training is documented to improve maximal muscle strength, power, and walking work efficiency as a result of adaptations in neuromuscular force developing factors.

CONCLUSIONS

In conclusion, improvements in these key determinants for physical health appear to be achievable in people with SMDs despite many being challenged by motivational difficulties with attending regular exercise and have beneficial implications for physical function during activities of daily living, lifestyle-related diseases, and early death.

Maximal isometric strength indices are associated with the oxygen cost of walking and running in recreationally active men and women

This study assessed the associations of maximal isometric strength and movement economy in 126 recreationally active men and women. Oxygen consumption was assessed through a graded treadmill test with 4-minute increments (4-12 km∙h^-1). Maximal isometric leg extensor, leg flexor and handgrip strength were assessed by isometric dynamometry. Models of best fit for gross oxygen cost and gross caloric unit cost were observed across the majority of velocities when the leg extensor/flexor strength ratio and handgrip strength were combined (R² = 0.207-0.525 and R² = 0.152-0.475, respectively). Additionally, the oxygen cost differed statistically for the majority of velocities when participants were split by the median of leg extensor strength (12.3-26.3 ml∙kg^-1∙km^-1, p < 0.05) and the average of all strength variables (13.9-30.3 ml∙kg^-1∙km^-1, p < 0.05). Our data underline the importance of maintaining maximal strength in order to perform activities with low to moderate oxygen demands.

On the simple calculation of walking efficiency without kinematic information for its convenient use

BACKGROUND

Since walking is a daily activity not to require the maximal effort in healthy populations, a very few universal bio-parameters and/or methods have been defined to evaluate individual walking characteristics in those populations. A concept of "economy" is a potential candidate; however, walking economy highly depends on speed, so direct comparisons of economy values are difficult between studies. We investigated whether the vertical component of net walking "efficiency" (Eff_vert; %) is constant across speed. In that case, direct comparisons of Eff_vert will be possible between studies or individuals at any voluntary speed.

METHODS

Thirty young male participants walked at eight speeds on the level or ± 5% gradients, providing vertical speeds (v_vert). Differences in energy expenditure between level and uphill or downhill gradients (ΔEE) were calculated. The metabolic rate for vertical component (MR_vert) was calculated by multiplying ΔEE with body mass (BM). The mechanical power output for vertical component (P_mech) was calculated by multiplying BM, gravitational acceleration, and v_vert. Eff_vert was obtained from the ratio of P_mech to MR_vert at each v_vert. Delta efficiency (Delta-E; %) was also calculated from the inverse slope of the regression line representing the relationship of P_mech to MR_vert.

RESULTS

Upward Eff_vert was nearly constant at around 35% and downward Eff_vert ranged widely (49-80%). No significant differences were observed between upward Delta-E (35.5 ± 8.8%) and Eff_vert at any speeds, but not between downward Delta-E (44.9 ± 12.8%) and Eff_vert.

CONCLUSIONS

Upward ΔEE could be proportional to v_vert. Upward, but not downward, Eff_vert should be useful not only for healthy populations but also for clinical patients to evaluate individual gait characteristics, because it requires only two metabolic measurements on the level and uphill gradients without kinematic information at any voluntary speed.

TRIAL REGISTRATION

UMIN000017690 (R000020501; registered May 26th, 2015, before the first trial) and UMIN000031456 (R000035911; registered Feb. 23rd, 2018, before the first trial).

Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly

Aging is associated with a progressive decline in skeletal muscle function, then leading to impaired exercise tolerance. Maximal strength training (MST) appears to be a practical and effective intervention to increase both exercise capacity and efficiency. However, the underlying physiological mechanisms responsible for these functional improvements are still unclear. Accordingly, the purpose of this study was to examine the intramuscular and metabolic adaptations induced by 8 weeks of knee-extension MST in the quadriceps of 10 older individuals (75 ± 9 yrs) by employing a combination of molecular, magnetic resonance ¹H-imaging and ³¹P-spectroscopy, muscle biopsies, motor nerve stimulation, and indirect calorimetry techniques. Dynamic and isometric muscle strength were both significantly increased by MST. The greater torque-time integral during sustained isometric maximal contraction post-MST (P = 0.002) was associated with increased rates of ATP synthesis from anaerobic glycolysis (PRE: 10 ± 7 mM·min^-1; POST: 14 ± 7 mM·min^-1, P = 0.02) and creatine kinase reaction (PRE: 31 ± 10 mM·min^-1; POST: 41 ± 10 mM·min^-1, P = 0.006) such that the ATP cost of contraction was not significantly altered. Expression of fast myosin heavy chain, quadriceps muscle volume, and submaximal cycling net efficiency were also increased with MST (P = 0.005; P = 0.03 and P = 0.03, respectively). Overall, MST induced a shift toward a more glycolytic muscle phenotype allowing for greater muscle force production during sustained maximal contraction. Consequently, some of the MST-induced improvements in exercise tolerance might stem from a greater anaerobic capacity to generate ATP, while the improvement in exercise efficiency appears to be independent from an alteration in the ATP cost of contraction.

Implementing resistance training in the rehabilitation of coronary heart disease: A systematic review and meta-analysis

BACKGROUND

Resistance training has demonstrated efficacy in cardiac rehabilitation programs, but the optimal prescription of resistance training is unknown. This systematic review with meta-analysis compared the effectiveness of cardiac rehabilitation consisting of resistance training either alone (RT) or in combination with aerobic training (CT) with aerobic training only (AT) on outcomes of physical function. Further, resistance training intensity and intervention duration were examined to identify if these factors moderate efficacy.

METHODS

Six electronic databases were searched to identify studies investigating RT, coronary heart disease and physical function. The overall quality of evidence was assessed using the GRADE approach. Meta-analyses were performed when possible and qualitative analysis was performed for the remaining data.

RESULTS

Improvements in peak oxygen uptake (WMD: 0.61, 95% CI: 0.20-1.10), peak work capacity (SMD: 0.38, 95% CI: 0.11-0.64) and muscular strength (SMD: 0.65, 95% CI: 0.43-0.87) significantly favoured CT over AT with moderate quality evidence. There was no evidence of a difference in effect when comparing RT and AT. Shorter duration CT was superior to shorter duration AT for improving peak oxygen uptake and muscular strength (low quality evidence) while longer duration CT was only superior to longer duration AT in improving muscular strength (moderate quality evidence).

CONCLUSIONS

CT is more beneficial than AT alone for improving physical function. Although preliminary findings are promising, more high-quality evidence is required to determine the efficacy of high intensity resistance training. Shorter duration interventions that include resistance training might allow patients to return to their normal activities of daily living earlier.

Relationships between lower body strength and the energy cost of treadmill walking in a cohort of healthy older adults: a cross-sectional analysis

PURPOSE

Gait speed is associated with survival in older adults and it was suggested that an elevated energy cost of walking (Cw) is an important determinant of gait speed reduction. Thus far, little is known about the factors that contribute to a lower Cw but it was shown that lower body strength training could reduce the Cw. Therefore, the objective of this study was to investigate the relationship between lower body strength and the Cw in a cohort of healthy older adults.

METHODS

A total of 48 participants were included in this study (70.7 ± 5.4 years). After a geriatric and a neuropsychological assessment, participants underwent a fitness testing protocol which included a maximal oxygen uptake test, assessment of the Cw at 4 km h^-1 on a treadmill, an isokinetic maximal strength test for the ankle, knee and hip joints and a body composition assessment. Relationships between strength variables and the Cw were assessed with partial correlations and linear regression analyses.

RESULTS

Hip extensors and hip flexors peak torque was significantly correlated with the Cw (r = -0.36 and -0.32, respectively; p < 0.05). A tendency towards significance was identified for the ankle plantar flexors (r = -0.25, p = 0.09). Hip extensors peak torque was the only significant neuromuscular parameter included in the linear regression analysis (p < 0.05).

CONCLUSION

These results show that hip extensors are an important muscle group with regards to the Cw measured on a treadmill in this cohort of healthy older adults.

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).

Effects of endurance, circuit, and relaxing training on cardiovascular risk factors in hypertensive elderly patients

Recommendations for prevention of cardiovascular diseases (CVDs) risk factors among older adults highlighted the importance of exercise-based interventions, including endurance training (ET). However, the evidence of efficacy of other interventions based on short-bouts of exercise (circuit training, CT), and the practice of breath-control and meditation (relaxing training, RT) is growing. The aim of this study was to elucidate if CT or RT are equally effective in CVD risk factors reduction compared to ET. To this purpose, in 40 elderly participants, with clinically diagnosed grade 1 hypertension, resting blood pressure, blood glucose, and cholesterol levels, peak oxygen uptake ([Formula: see text]), mechanical efficiency and quality of life were evaluated before and after 12 weeks of ET, CT, and RT treatments. Resting blood pressure reduced significantly in all groups by ∼11 %. In ET, blood cholesterol levels (-18 %), [Formula: see text] (+8 %), mechanical efficiency (+9 %), and quality of life scores (+36 %) ameliorated. In CT blood glucose levels (-11 %), [Formula: see text] (+7 %) and quality of life scores (+35 %) were bettered. Conversely, in RT, the lower blood pressure went along only with an improvement in the mental component of quality of life (+42 %). ET and CT were both appropriate interventions to reduce CVDs risk factors, because blood pressure reduction was accompanied by decreases in blood glucose and cholesterol levels, increases in [Formula: see text], mechanical efficiency, and quality of life. Although RT influenced only blood pressure and quality of life, this approach would be an attractive alternative for old individuals unable or reluctant to carry out ET or CT.

Haemodynamics of aerobic and resistance blood flow restriction exercise in young and older adults

PURPOSE

Light-load blood flow restriction exercise (BFRE) may provide a novel training method to limit the effects of age-related muscle atrophy in older adults. Therefore, the purpose of this study was to compare the haemodynamic response to resistance and aerobic BFRE between young adults (YA; n = 11; 22 ± 1 years) and older adults (OA; n = 13; 69 ± 1 years).

METHOD

On two occasions, participants completed BFRE or control exercise (CON). One occasion was leg press (LP; 20 % 1-RM) and the other was treadmill walking (TM; 4 km h(-1)). Haemodynamic responses (HR, Q, SV and BP) were recorded during baseline and exercise.

RESULT

At baseline, YA and OA were different for some haemodynamic parameters (e.g. BP, SV). The relative responses to BFRE were similar between YA and OA. Blood pressures increased more with BFRE, and also for LP over TM. Q increased similarly for BFRE and CON (in both LP and TM), but with elevated HR and reduced SV (TM only).

CONCLUSION

While BFR conferred slightly greater haemodynamic stress than CON, this was lower for walking than leg-press exercise. Given similar response magnitudes between YA and OA, these data support aerobic exercise being a more appropriate BFRE for prescription in older adults that may contribute to limiting the effects of age-related muscle atrophy.

Multiple roads lead to Rome: combined high-intensity aerobic and strength training vs. gross motor activities leads to equivalent improvement in executive functions in a cohort of healthy older adults

The effects of physical activity on cognition in older adults have been extensively investigated in the last decade. Different interventions such as aerobic, strength, and gross motor training programs have resulted in improvements in cognitive functions. However, the mechanisms underlying the relationship between physical activity and cognition are still poorly understood. Recently, it was shown that acute bouts of exercise resulted in reduced executive control at higher relative exercise intensities. Considering that aging is characterized by a reduction in potential energy ([Formula: see text] max - energy cost of walking), which leads to higher relative walking intensity for the same absolute speed, it could be argued that any intervention aimed at reducing the relative intensity of the locomotive task would improve executive control while walking. The objective of the present study was to determine the effects of a short-term (8 weeks) high-intensity strength and aerobic training program on executive functions (single and dual task) in a cohort of healthy older adults. Fifty-one participants were included and 47 (age, 70.7 ± 5.6) completed the study which compared the effects of three interventions: lower body strength + aerobic training (LBS-A), upper body strength + aerobic training (UBS-A), and gross motor activities (GMA). Training sessions were held 3 times every week. Both physical fitness (aerobic, neuromuscular, and body composition) and cognitive functions (RNG) during a dual task were assessed before and after the intervention. Even though the LBS-A and UBS-A interventions increased potential energy to a higher level (Effect size: LBS-A-moderate, UBS-A-small, GMA-trivial), all groups showed equivalent improvement in cognitive function, with inhibition being more sensitive to the intervention. These findings suggest that different exercise programs targeting physical fitness and/or gross motor skills may lead to equivalent improvement in cognition in healthy older adults. Such results call for further investigation of the multiple physiological pathways by which physical exercise can impact cognition in older adults.

Maximal strength training in postmenopausal women with osteoporosis or osteopenia

Current guidelines recommend weight-bearing activities, preferably strength training for improving skeletal health in patients with osteoporosis. What type of strength training that is most beneficial for these patients is not established. Maximal strength training (MST) is known to improve 1-repetition maximum (1RM) and rate of force development (RFD), which are considered as important covariables for skeletal health. Squat exercise MST might serve as an effective intervention for patients with low bone mass. We hypothesized that 12 weeks of squat exercise MST would improve 1RM and RFD in postmenopausal women with osteoporosis or osteopenia and that these changes would coincide with improved bone mineral density (BMD) and bone mineral content (BMC), and serum markers of bone metabolism. The participants were randomized to a training group (TG, n = 10) or control group (CG, n = 11). The TG underwent 12 weeks of supervised squat exercise MST, 3 times a week, with emphasis on rapid initiation of the concentric part of the movement. The CG was encouraged to follow current exercise guidelines. Measurements included 1RM, RFD, BMD, BMC, and serum bone metabolism markers; type 1 collagen amino-terminal propeptide (P1NP) and type 1 collagen C breakdown products (CTX). At posttest, 8 participants remained in each group for statistical analyses. The TG improved the 1RM and RFD by 154 and 52%, respectively. Lumbar spine and femoral neck BMC increased by 2.9 and 4.9%. The ratio of serum P1NP/CTX tended to increase (p = 0.09), indicating stimulation of bone formation. In conclusion, squat exercise MST improved 1RM, RFD, and skeletal properties in postmenopausal women with osteopenia or osteoporosis. The MST can be implemented as a simple and effective training method for patients with reduced bone mass.

Submaximal oxygen cost during incremental exercise in children with developmental coordination disorder

There has been minimal evidence examining the differences in submaximal aerobic power between children with and without probable developmental coordination disorder (pDCD). This is important as most activities of daily living are performed at submaximal levels. The aim of this study was to examine the oxygen cost of work (VO2) performed during an incremental exercise protocol on a cycle ergometer. Subjects with pDCD (n=63) were matched for age and gender to 63 typically developing controls (12-13 years of age) using a nested case-control design. Motor coordination was assessed using the Movement Assessment Battery for Children. Children with pDCD had significantly lower VO2 peak values relative to controls (35.0 vs. 42.9 ml/kg/min, p<0.0001). At the submaximal level, mixed effects modeling demonstrated that, after controlling for relative body fat, and VO2 peak, children with pDCD had consistently greater oxygen cost (VO2 ml/kg/min) compared to controls at any given exercise intensity (p=0.0006). A significant interaction between pDCD and workload indicated that the difference in VO2 at higher workloads is greater than that at lower workloads (p=0.0004). Children with pDCD utilize more oxygen to sustain the same submaximal workload. The implication of these findings is that children with pDCD may experience earlier fatigue than well coordinated individuals when engaging in physical activity.

Executive functions, physical fitness and mobility in well-functioning older adults

The objective of this study was to examine the relationships between executive functions, physical fitness and mobility in well-functioning older adults. Forty-eight well functioning older adults (70.5±5.3years old; 20 men, 28 women) were included in this study. Two median splits were conducted based on each individual's performance for the 10MWT and TUG. Comparisons between groups of slower and faster individuals were made with regard to executive functions and physical fitness parameters. A correlational approach was used to assess the association between variables. Between groups comparisons revealed that faster individuals in mobility tests demonstrate better performances in measures of cognitive flexibility (0.68<g<0.90). After including covariates from the medical/social domain, significant correlations were established between faster mobility tests and better cognitive flexibility (TUG: r=0.565; 10MWT: r=0.324). Between groups comparisons also revealed that faster individuals in mobility tests presented higher physical fitness levels (aerobic: 0.49<g<0.77, strength: 0.34<g<1.31). Significant correlations were found between better physical fitness and better cognitive flexibility (strength: r=-0.380; VO2 peak: r=-0.325) even after including age, education, fat-free mass and gender as covariates. These results suggest that the TUG and the 10MWT could potentially help distinguish individuals with poor neuromuscular, aerobic and cognitive flexibility performances.

Maximal strength training improves work economy, rate of force development and maximal strength more than conventional strength training

This study compared maximal strength training (MST) with equal training volume (kg × sets × repetitions) of conventional strength training (CON) primarily with regard to work economy, and second one repetition maximum (1RM) and rate of force development (RFD) of single leg knee extension. In an intra-individual design, one leg was randomized to knee-extension MST (4 or 5RM) and the other leg to CON (3 × 10RM) three times per week for 8 weeks. MST was performed with maximal concentric mobilization of force while CON was performed with moderate velocity. Eight untrained or moderately trained men (26 ± 1 years) completed the study. The improvement in gross work economy was -0.10 ± 0.08 L min(-1) larger after MST (P = 0.011, between groups). From pre- to post-test the MST and CON improved net work economy with 31 % (P < 0.001) and 18 % (P = 0.01), respectively. Compared with CON, the improvement in 1RM and dynamic RFD was 13.7 ± 8.4 kg (P = 0.002) and 587 ± 679 N s(-1) (P = 0.044) larger after MST, whereas isometric RFD was of borderline significance 3,028 ± 3,674 N s(-1) (P = 0.053). From pre- to post-test, MST improved 1RM and isometric RFD with 50 % (P < 0.001) and 155 % (P < 0.001), respectively whereas CON improved 1RM and isometric RFD with 35 % (P < 0.001) and 83 % (P = 0.028), respectively. Anthropometric measures of quadriceps femoris muscle mass and peak oxygen uptake did not change. In conclusion, 8 weeks of MST was more effective than CON for improving work economy, 1RM and RFD in untrained and moderately trained men. The advantageous effect of MST to improve work economy could be due to larger improvements in 1RM and RFD.

Therapeutic effects of maximal strength training on walking efficiency in patients with schizophrenia - a pilot study

Background

Patients with schizophrenia frequently have disabling gait deficits. The net mechanical efficiency of walking (ϵ_net) is an accurate measure often used to evaluate walking performance. Patients with gait deficits have a reduced ϵ_net with excessive energy expenditure during sub-maximal walking. Maximal strength training (MST) improves ϵ_net in healthy individuals and is associated with reduced risk of mortality. The aim of this study was to investigate whether MST improves ϵ_net in patients with schizophrenia.

Methods

Patients (ICD-10 schizophrenia, schizotypal or delusional disorders (F20-F29)) were included in a non-randomized trial. Patients were assigned to one of two groups: 1) MST consisting of 4x4 repetitions at 85-90% one repetition maximum (1RM) performed in a leg press apparatus or 2) playing computer games (CG). Both groups carried out their activity three days per week for eight weeks. 1RM, ϵ_net at 60 watt walking, peak oxygen uptake (VO_2peak), the Positive and Negative Syndrome Scale (PANSS) and the 36-items short form (SF-36) were measured pre and post intervention.

Results

The baseline ϵ_net was 17.3 ± 1.2% and 19.4 ± 3.0% in the MST (n = 6) and CG groups (n = 7), respectively, which is categorized as mechanical inefficiency. The MST group improved 1RM by 79 kg (p = 0.006) and ϵ_net by 3.4% (p = 0.046) more than the CG group. The MST group improved 1RM and ϵ_net, by a mean of 83 kg (p = 0.028) and 3.4% (p = 0.028), respectively. VO_2peak at baseline was 34.2 ± 10.2 and 38.3 ± 9.8 ml·kg^-1·min^-1 in the MST and CG groups, respectively, and did not change (p > 0.05). No change was observed in PANSS or SF-36 (p > 0.05).

Conclusions

MST improves 1RM and ϵ_net in patients with schizophrenia. MST could be used as a therapeutic intervention for patients with schizophrenia to normalize their reduced ϵ_net.

Effects of high aerobic intensity training in patients with schizophrenia: a controlled trial

BACKGROUND

Patients with schizophrenia have a high risk of cardiovascular disease (CVD). High aerobic intensity training (HIT) improve peak oxygen uptake (VO(2peak)), net mechanical efficiency of walking and risk factors for CVD but has not been investigated in patients with schizophrenia.

AIMS

To investigate effects from HIT on VO(2peak), net mechanical efficiency of walking and risk factors for CVD in patients with schizophrenia.

METHODS

25 inpatients (F20-29, ICD-10) were allocated to either HIT or playing computer games (CG), 3 days per week for 8 weeks. HIT consisted of 4 × 4-min intervals with 3-min break periods, at 85-95% and 70% of peak heart rate, respectively.

RESULTS

12 and seven patients completed HIT and CG, respectively. The baseline VO(2peak) in both groups combined (n = 19) was 36.8 ± 8.2 ml/kg/min and 3.12 ± 0.55 l/min. The HIT group improved VO(2peak) by 12% from 3.17 ± 0.59 to 3.56 ± 0.68 l/min (P < 0.001), more than the CG group (P = 0.014). Net mechanical efficiency of walking improved by 12% in the HIT group from 19.8 ± 3.0% to 22.2 ± 4.5% (P = 0.005), more than the CG group (P = 0.031). The psychiatric symptoms, expressed as the Positive and Negative Syndrome Scale (PANSS) and the Calgary Depression Scale for Schizophrenia (CDSS), did not improve in either group.

CONCLUSIONS

VO(2peak) and net mechanical efficiency of walking improved significantly by 8 weeks of HIT. HIT should be included in rehabilitation in order to improve physical capacity and contribute risk reduction of CVD.