The Effect of Structured Exercise Intervention on Intensity and Volume of Total Physical Activity

This study aimed to investigate the effects of a 12-week structured exercise intervention on total physical activity and its subcategories. Twenty-three overweight or obese middle aged men with impaired glucose regulation were randomized into a 12-week Nordic walking group, a power-type resistance training group, and a non-exercise control group. Physical activity was measured with questionnaires before the intervention (1–4 weeks) and during the intervention (1–12 weeks) and was expressed in metabolic equivalents of task. No significant change in the volume of total physical activity between or within the groups was observed (p > 0.050). The volume of total leisure-time physical activity (structured exercises + non-structured leisure-time physical activity) increased significantly in the Nordic walking group (p < 0.050) but not in the resistance training group (p > 0.050) compared to the control group. In both exercise groups increase in the weekly volume of total leisure-time physical activity was inversely associated with the volume of non-leisure-time physical activities. In conclusion, structured exercise intervention did not increase the volume of total physical activity. Albeit, endurance training can increase the volume of high intensity physical activities, however it is associated with compensatory decrease in lower intensity physical activities. To achieve effective personalized exercise program, individuality in compensatory behavior should be recognised.

Key Points

• Structured NW or RT training does not increase the volume of total physical activity.
• NW intervention can increase the volume of higher intensity activities.
• The increased in volume of LTPA induced by the structured NW and RT interventions was associated with the decreased volume of NLTPA.

Key words: Nordic walking, resistance training, energy expenditure, thermogenesis, glucose intolerance     

Effect of Home-Based Well-Rounded Exercise in Community-Dwelling Older Adults

The purpose of this study was to assess the efficacy of a home-based well-rounded exercise program (WREP) in older adults. Forty sedentary community-dwelling older adults were randomly assigned to an exercise group (n = 23; aged 62-80 yr, average: 69.2 ± 5.2; 12 men and 11 women) or a control group (n = 17; aged 63-85 yr, average: 70.1 ± 6.6; 5 men and 12 women). The exercise group performed a 12-wk WREP which included aerobic exercise (walking) on about 3 days·wk^-1 for 37 min·day^-1; elastic band-based resistance exercises for the major muscle groups on about 3 days·wk^-1 for 26 min; and flexibility exercises (stretching) on about 4 days·wk^-1 for 19 min·day^-1. General physical characteristics, functional strength (Arm Curl [AC], Chair Stand [CS]), dynamic balance and agility (Up & Go [UG]), flexibility (Back Scratch [BS], Sit & Reach [SR]), and endurance (12-min walk [12-MW]) were measured. Following the 12-wk home-based WREP, improvements were observed in AC, CS, UG, BS, SR and 12-MW for the exercise group but not for the control group. These results suggest that the home-based WREP can improve overall fitness in older adults.

Key Points

• Walking, elastic band exercise and stretching were prescribed as a Well-Rounded Exercise Program for older adults.
• By combining aerobic, resistance and flexibility exercises, a Well-Rounded Exercise Program was effective for improving endurance, functional strength, dynamic balance and agility, and flexibility.
• Community-based exercise classes motivated older adults to perform home-based exercises.

Key words: Physical fitness, aerobic exercise, resistance exercise, flexibility exercise, adherence     

Low-Volume Walking Program Improves Cardiovascular-Related Health in Older Adults

Although numerous sources of evidence show that regular physical activity is beneficial to health, most individuals do not engage in a sufficient amount of physical activity to meet the guidelines set out by expert panels. In addition, the minimum amount of physical activity associated with reduced cardiovascular disease risk markers is not clear in older adults. The purpose of this study was to determine the effects of a 12-week walking program involving an exercise volume below the current minimum physical activity recommendation on cardiovascular disease risk markers in older adults. The participants were recruited from the following two groups separately: a walking group (n = 14) and a control group (n = 14). In the walking group, participants walked 30 to 60 minutes per session on 2 days per week for 12 weeks (average walking time, 49.4 ± 8.8 min/session). Plasma oxidised low-density lipoprotein concentrations tended to be lower than baseline values in the walking group after 12 weeks (paired t-test, p = 0.127). The ratio of oxidised low-density lipoprotein to high-density lipoprotein cholesterol was significantly lower than the baseline ratio in the walking group after 12 weeks (paired t-test, p = 0.035). Resting systolic blood pressure and diastolic blood pressure were significantly lower than baseline values in the walking group after 12 weeks (paired t-tests, p = 0.002, p < 0.0005, respectively). Our findings demonstrate that a 12-week walking program comprising a low volume of physical activity confers a benefit to cardiovascular-related health in older adults.

Key Points

• It is important to consider baseline physical activity levels when evaluating physical activity program.
• Being physically active is important to reduce the potential risk marker of cardiovascular disease in older adults.
• These data imply that a small volume of 12-week walking program confers a benefit to cardiovascular-related health in older adults.

Key words: blood pressure, exercise, lipid metabolism, older adults, oxidised low-density lipoprotein     

Expression of Heat Shock Proteins (HSPs) in Aged Skeletal Muscles Depends on the Frequency and Duration of Exercise Training

The skeletal muscle in aged rats adapts rapidly following a period of exercise. This adaptation includes structural remodeling and biochemical changes such as an up-regulation of antioxidant enzymes, content of stress and heat shock proteins (HSPs). However, the associated molecular mechanisms mediating different types of exercise training-induced adaptations are not yet completely understood. Therefore, the purpose of this study was to investigate the effects of duration and frequency exercise on the expression of HSPs, antioxidant enzymes, and mitogen-activated protein kinase (MAPKs) in the skeletal muscles of aged rats. Young (3-month-old) and aged (20-month-old) male Sprague-Dawley rats were randomly assigned to 6 groups and extensor digitorum longus (EDL; fast twitch muscle fiber) and soleus (SOL; slow twitch muscle fiber) skeletal muscles were collected immediately. The expression pattern of HSPs in skeletal muscles was decreased in old groups compared with young groups. Especially, HSPs showed lower expression in SOL than EDL muscle. Interestingly, HSPs in aged rats was increased significantly after S1 (single long-duration; 1×30 min, 5 days/week for 6 weeks) and M1 types (multiple short-duration; 3×10 min·day⁻¹, 5 days·week⁻¹ for 6 weeks) than S2 (single long-duration; 1×30 min, 3 days/week for 6 weeks) and M2 (multiple short-duration; 3×10 min·day⁻¹, 3 days·week⁻¹ for 6 weeks) types of exercise training. Also, superoxide dismutase (SODs) showed similar expression as HSP did. On the contrary, the p-ERK and p-JNK were down regulated. In addition, p-p38 level in the SOL muscle was activated markedly in all exercise groups. These results demonstrate that increasing of HSP expression through duration and frequency exercise can lead to protection and training-induced adaptation against aging-induced structural weakness in skeletal muscles.

Key points

• The expression of heat shock proteins (HSPs) in aged rats was increased significantly after single long-duration (S1) and multiple short-duration (M1) types than S2 and M2 types of exercise training in soleus (SOL) skeletal muscles.
• Superoxide dismutase (SODs) showed similar expression as HSPs did. On the contrary, the p-ERK and p-JNK were down regulated. In addition, p-p38 level in the SOL muscle was activated markedly in all exercise groups.
• Induction of HSPs and SODs by high duration and frequency of exercise training such as S1 and M1 types with concomitant MAPKs pathway depending on the type of muscles.
• The frequency and duration of exercise training could affect the functional adaptation and protection against aging-induced structural weakness of skeletal muscles through changing expression of related molecules.

Key words: Aging, multiple short-duration exercise training, single long-duration exercise training, heat shock protein, superoxide dismutase, mitogen-activated protein kinase     

The Effects of Intermittent Exercise on Physiological Outcomes in an Obese Population: Continuous Versus Interval Walking

This study compared the effects of 12 weeks of caloric restriction and interval exercise (INT) and caloric restriction and continuous aerobic exercise (CON) on physiological outcomes in an obese population. Forty-four individuals (BMI ≥ 30 kg·m^-2) were randomised into the INT or CON group. Participant withdrawal resulted in 12 and 14 participants in the INT and CON groups, respectively. All participants were on a strict monitored diet. Exercise involved two 15-min bouts of walking performed on five days per week. Interval exercise consisted of a 2:1 min ratio of low-intensity (40-45% VO_2peak) and high- intensity (70-75% VO_2peak) exercise, while the CON group exercised between 50-55% VO_2peak. Exercise duration and average intensity (%VO_2peak) were similar between groups. There were no significant differences (p > 0.05) between the two groups for any variable assessed apart from very low density lipoprotein (VLDL-C), which significantly decreased over time in the INT group only (p < 0.05, d = 1.03). Caloric restriction and interval exercise compared to caloric restriction and continuous aerobic exercise resulted in similar outcome measures apart from VLDL-C levels, which significantly improved in the INT group only.

Key points

• Twelve weeks of interval exercise and caloric restriction resulted in significant improvement in very low density lipoprotein cholesterol in an obese population, as compared to continuous aerobic exercise and caloric restriction.
• Twelve weeks of either interval exercise or continuous exercise resulted in similar improvements in aerobic fitness in an obese population.

Key words: Interval training, body fat, fitness, metabolism     

Peak Fat Oxidation Rate During Walking in Sedentary Overweight Men and Women

The aim of this study was to determine the relative exercise intensity that elicits maximal fat oxidation during walking in inactive and overweight men and women and evaluate any possible sex differences. Forty six healthy, sedentary, overweight men (age: 36.3 ± 1.3 years, body fat: 28.8 ± 0.8%, n = 28, mean ± SE) and women (age: 36.6 ± 1.8 years, body fat: 37.1 ± 0.8%, n = 18) participated in the study. Fat oxidation was calculated from expired air analysis using indirect calorimetry during an incremental treadmill walking test. Peak fat oxidation rate (PFO) was higher in men compared to women (0.31 ± 0.02 vs. 0.20 ± 0.02 g.min^-1; p < 0.001), but this difference disappeared when PFO was scaled per kg fat-free mass (4. 36 ± 0.23 vs. 3.99 ± 0.37 mg.kg fat free mass^-1.min^-1). Also, the relative exercise intensity at which PFO occurred was similar for men and women and corresponded to 40.1 ± 1.8 and 39. 5 ± 2.3% of maximal oxygen uptake (VO₂max) and 60.0 ± 1.4 and 57.8 ± 1.4% of maximal heart rate, respectively. The walking speed corresponding to PFO was 5.5 ± 0.2 and 5.0 ± 0.1 km·h^-1 for men and women, respectively. Regression analysis showed that sex, FFM and VO₂max were significant predictors of PFO expressed in g.min^-1 (adjusted R² = 0.48, p = 0.01). However when PFO was scaled per kg FFM, only a small part of the variance was explained by VO₂max (adjusted R² = 0.12, p < 0.05). In conclusion, peak fat oxidation rate and the corresponding relative exercise intensity were similar in male and female overweight and sedentary individuals, but lower compared to those reported for leaner and/or physically active persons. Walking at a moderate speed (5.0-5.5 km·h^-1) may be used as a convenient way to exercise at an intensity eliciting peak fat oxidation in overweight individuals.

Key points

• Peak fat oxidation rate scaled per kg fat-free mass and the corresponding relative exercise intensity are similar in male and female overweight and sedentary individuals, but lower compared to those reported for leaner and/or physically active persons.
• Walking at a moderate speed (5.0-5.5 km.h^-1) may be used as a convenient way to exercise at an intensity eliciting peak fat oxidation in overweight individuals.
• The relationship between %HRmax and %VO₂max in overweight individuals is different from that reported for normal-weight adults and should be taken into account to optimize exercise intensity using heart rate in obese individuals.
• Due to the low intensity corresponding to peak fat oxidation in overweight and sedentary persons and the inter-individual differences, exercise intensity for health benefits should be prescribed following individual testing.

Key words: Exercise intensity, calorimetry, substrate utilisation     

Validation of the Mywellness Key in Walking and Running Speeds

This study was performed to assess the validity of the MyWellness Key (MWK) accelerometer during a treadmill-based protocol. The identification of different exercise intensities is imperative to objectively measure time spent at a specified exercise intensity. Thirty subjects, 15 men and 15 women (age = 24.5 ± 2.6 years; body mass index = 22.5 ± 2.5 kg·m^-1), participated in a 4-phase treadmill protocol (5 minutes each one) using three different walking velocities (3, 4.5, and 6 km·h^-1) and run (8 km·h^-1) while outfitted with a MWK uniaxial accelerometer. Oxygen consumption was measured by indirect calorimetry (IC_VO2). Results: The relationship between VO₂ predicted from MWK (MWK_VO2) and oxygen consumption (VO₂ (IC_VO2)), yielded a high and significant correlation (r = 0. 944; p < 0.001) with standard error of estimate (SEE) = 2.42 mL·kg^-1·min^-1. The average differences between the two methods (MWK_VO2 - IC_VO2) were -0.79 (-8. 8% at 3 km·h^-1), -0.02 (-0.2% at 4.5 km·h^-1), 0.51 (3.3% at 6 km·h^-1) and -0.74 (-2.7% at 8 km·h^-1) ml·kg^-1·min^-1. Only the 3 km·h^-1 speed showed a difference when compared to the criterion measure (p < 0.001). Bland and Altman analysis revealed less than a 1 MET difference in the mean at each point estimate and relatively tight distribution with the standard errors, especially with the 2 moderate walking speeds. Conclusions: We found a high correlation between oxygen utilization and the MWK with low standard errors estimates. This indicates that this accelerometer can be used to identify exercise intensities that are related to walking and running.

Key points

• First laboratory validation of a new uniaxial accelerometer, the MyWellness Key.
• Results indicate a good exercise intensity prediction during walking at moderate to high speeds.
• Comparing with other laboratory validations, MyWellness Key exercise intensity detection is aligned with other accelerometers.
• MyWellness Key can be used to give valid measurements for a range of ambulatory activity in addition to the capabilities to give real-time feedback to the participant in health promotion studies.

Key words: Accelerometry, Indirect Calorimetry, Measurement, Physical Activity     

Cardiorespiratory Characteristics and Cholesterol Responses to a Single Session of Heavy Leg Press Exercise

The effect of resistance exercise on blood lipids is not clear yet. The purpose of this study was to examine the cholesterol responses to a heavy resistance leg press exercise emphasizing on the eccentric movement 24 and 48 hours following exercise and to quantify the cardiorespiratory responses of the exercise bout in an attempt to clarify the exercise characteristics that may be responsible for the effects of heavy resistance exercise on blood lipids. Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yrs (76.2 ± 2.5 kg, 1.79 ± 0.02 m) performed a session of heavy RE emphasizing on the eccentric movement consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. Venous blood samples were obtained at rest (control) and 24 and 48 hours following exercise. Average VO₂ at rest was 4.0 ± 0.4 ml·min⁻¹·kg⁻¹, during exercise 19.6 ± 0.2 ml·min⁻¹·kg⁻¹ and during the 180 sec recovery period between sets 12.5 ± 0.2 ml·min⁻¹·kg⁻¹. RER values decreased with the progression of the exercise and were significantly lower during the last four sets compared with the first four sets of the exercise session. Resting heart rate was 67 ± 2 bpm, and maximum heart rate during exercise was 168 ± 1 bpm. Serum creatine kinase was significantly elevated on day 1 (1090 ± 272 U·L⁻¹, p < 0.03) and peaked on day 2 (1230 ± 440 U·L⁻¹ p < 0. 01). Total cholesterol, HDL cholesterol and calculated LDL cholesterol concentration did not change significantly following with exercise. This protocol of heavy resistance exercise has no effect on TC or cholesterol sub-fraction concentration 24 and 48 hours following exercise which may be due to the low energy expenditure of the exercise and/or to the gender of the participants.

Key points

• Repeated sets of heavy resistance exercise significantly increase oxygen uptake both during exercise and the following recovery period.
• Even though exercise was of low volume (8 sets x 6 repetitions) the elevated oxygen uptake during the rest intervals in combination with the total exercise session duration (26 min) resulted in aerobic energy expenditure that is equivalent to low to moderate intensity cycling.
• Leg press resistance exercise emphasizing on the eccentric movement that caused muscle damage had no effect on total cholesterol, HDL-C and LDL-C during the two days following exercise in young healthy male subjects.

Key words: Muscle damage, energy expenditure, total cholesterol, HDL, oxygen uptake.     

Influence of Two Different Exercise Programs on Physical Fitness and Cognitive Performance in Active Older Adults: Functional Resistance-Band Exercises vs. Recreational Oriented Exercises

This study examines the impact of a resistance-band functional exercise program, compared with a recreational exercise program, on physical fitness and reaction times in persons older than 60 years. Fifty-four community-dwelling volunteers (71.76 ± 6.02 years) were assigned to a specific exercise program: Functional activity program (focused on resistance-band multi-joint activities; experimental group, EG), or recreational physical activity program (with gross motor activities of ludic content; control group, CG). Before and after the intervention, we determined cognitive capacity in terms of simple reaction time (S-RT), choice reaction time (C-RT) and fitness. In both groups physical performance improved, though this improvement was more marked in the EG for grip strength, arm strength and gross motor abilities (p < 0.05). Reaction times were better only in EG (S-RT = 10.70%, C-RT = 14.34%; p < 0.05) after the corresponding physical training intervention. The training period showed no effect on the moderate relationship between both RT and gross motor abilities in the CG, whereas the EG displayed an enhanced relationship between S-RT and grip-strength as well as the C-RT with arm strength and aerobic capacity (r ~ 0.457; p < 0.05). Our findings indicate that a functional exercise program using a resistance band improves fitness and cognitive performance in healthy older adults.

Key points

• Better cognitive processes can be achieved as physical condition improves
• Exercise sessions of a more recreational type do not seem to constitute a stimulus able to improve both physical and cognitive performance in healthy active older adults
• The improvement of cognitive function, as assessed through reaction times, seems more linked to the workload and strength component of the training program.

Key words: Aging, reaction time, physical activity program, cognitive capacity     

Development Of a Field Test for Evaluating Aerobic Fitness in Middle-Aged Adults: Validity of a 15-M Incremental Shuttle Walk and Run Test

The purpose of this study was to develop a standardized and externally paced field test (15-m Incremental Shuttle Walk and Run Test [15mISWRT]), incorporating an incremental and progressive structure, to assess aerobic fitness in middle-aged adults. 68 middle-aged men performed three tests in random order between one to two week intervals: 15-m ISWRT, cardiopulmonary exercise test (CPX), and 1500-m fast walk. Variables evaluated were 15-m ISWRT performance (distance completed), VO₂max measured by CPX, 1500-m fast walk performance (walking time), and HR response in 15-m ISWRT and 1500-m fast walk. Validity of the 15-m ISWRT was tested by comparing the associations among the 15-m ISWRT performance, VO₂max and the 1500-m fast walk performance. Changes in HR response during the 15-m ISWRT and the 1500-m fast walk were also compared. Correlations between each variable were as follows: the correlation between 15- m ISWRT performance and VO₂max was very high, r = 0.86 (p < 0.01), the correlation between the 1500-m fast walk and VO₂max was r = −0.51 (p < 0.01). HR response during the 15-m ISWRT gently increased initially, whereas HR response during the 1500-m fast walk rapidly increased from the start. In conclusion, our findings indicate that the 15-m ISWRT is valid and safe for evaluating VO₂max in middle-aged adults.

Key points

• The 15-m ISWRT is valid and safe for evaluating VO₂max in middle-aged adults.
• In comparison with the 1500-m fast walk, the 15-m ISWRT may be a more favourable field-based assessment of aerobic fitness in the middle-aged adults.
• The 15-m ISWRT could become a valid means for evaluating aerobic fitness as an alternative to CPX in institutions and situations where CPX is difficult to implement.

Key words: Maximal oxygen uptake, heart rate, 20m shuttle run test, shuttle walking test, cardiopulmonary exercise test     

The Effect of Chinese Yuanji-Dance on Dynamic Balance and the Associated Attentional Demands in Elderly Adults

Walking performance changes with age. This has implications for the problem of falls in older adults. The aim of this study was to investigate the effects of Yuanji-Dance practice on walking balance and the associated attention demand in healthy elderly. Fifteen community-dwelling elderly (comparison group, no regular exercise habit) and fifteen Yuanji- Dance elderly (exercise group, dancing experience: 5.40 ± 1.95 years), aged 60-70 years, were included in this study. The subjects in exercise group participated in a 90-minute Yuanji-Dance practice at least three times per week and the comparison group continued their normal daily physical activity. Walking balance measures (including walking velocity, step length, step width, and percentage of time spent in double limb support, COM velocity and COM-COP inclination angles) and attentional demand tests (button reaction time and accuracy) were conducted under different conditions. Our results showed that stride lengths, walking velocities, peak A/P velocities (AP V) of the COM, medial COM-COP inclination (M angle) angles, reaction time, and accuracy decrease significantly as the dual-task (walking plus hand button pressing tasks) applied for either the comparison or exercise groups. These results demonstrated that walking performance is attenuated in our elderly participants as the cognitive tasks applied. Analysis also identified a significantly faster RT for our exercise group both in standing and walking conditions. This may indicate that physical exercise (Yuanji-Dance) may have facilitating effects on general cognitive and perceptual- motor functions. This implies that Chinese Yuanji-Dance practice for elderly adults may improve their personal safety when walking especially under the condition of multiple task demand.

Key points

• The purpose of this study was to investigate the training effects of a Chinese traditional exercise, Yuanji-Dance, on walking balance and the associated attention demand in the healthy elderly.
• Walking performance is attenuated in elderly participants as the cognitive tasks applied.
• A significantly faster reaction time for our exercise group both in standing and walking conditions.
• Yuanji-Dance exercise training can improve the information processing speed of elderly people and has no influence of the dynamic walking balance.

Key words: Yuanji-Dance, exercise, balance, attention     

IGF-I and FGF-2 Responses to Wingate Anaerobic Test in Older Men

Reduced activity of the potent anabolic effectors: insulin-like growth factor-I (IGF-I) and fibroblast growth factor-2 (FGF-2), play a role in aging associated muscle loss. The effect of fitness level on IGF-I and FGF-2 responses to all-out anaerobic exercise in older men was studied. Twenty four healthy older males: 12 higher fit (58 ± 1y) and 12 lower fit (59 ± 1y) underwent the Wingate anaerobic test. Serum levels of IGF-I and FGF-2 were measured before, immediately after exercise, and 50 min into recovery. Immediately post exercise, the average peak power output and serum lactate were higher (p < 0.05) in the higher fit (446.0 ± 14. 9 kgm·min^-1 for mean (± SD) peak power and 12.6 ± 1.1 mml·l^-1 for lactate) compared with the lower fit individuals (284.0 ± 6.5 kgm·min^-1 and 8.5 ± 0.7 mml·l^-1, respectively). Pre-exercise IGF-I was lower and FGF-2 was higher in the higher fit (335.0 ± 54.0 ng·ml^-1 and 1.6 ± 0.1 ng·ml^-1, respectively) compared with lower fit individuals (402.0 ± 50.0 ng·ml^-1 and 1.4 ± 0.2 ng·ml^-1, respectively). Following the anaerobic exercise, in both groups, FGF-2 decreased dramatically (p < 0.05); in the higher fit individuals FGF-2 level was 0.4 ± 0.1 pg·ml^-1 compared to 0.1 ± 0.02 pg·ml^-1 in the lower fit individuals. In contrast to FGF-2, IGF-I increased transiently to levels of 405.0 ± 62.0 ng·ml^-1 in the higher fit individuals and to levels of 436 ± 57.0 ng·ml^-1 in the lower fit individuals. However, the IGF-I elevation was significant (p < 0. 05) only in the higher fit individuals. In conclusion, the present study demonstrates that during aging, fitness level can alter circulating levels of IGF-I and FGF-2. Furthermore, fitness level can affect the response of both mediators to all-out anaerobic exercise.

Key points

• The present study suggests that during aging, fitness level can alter circulating levels of IGF-I and FGF-2.
• Furthermore, fitness level can affect the response of both mediators to all-out anaerobic exercise.
• Anaerobic muscle activity is represented in many daily life activities of elderly individuals.
• This may have clinical implications during aging, where the declined activity of growth factors is a major determinant of the loss of muscle strength and function.

Key Words: Anaerobic exercise, aging, growth factors, hypertrophy, angiogenesis     

Effects of Unstable Shoes on Energy Cost During Treadmill Walking at Various Speeds

In recent years, shoes having rounded soles in the anterior-posterior direction have been commercially introduced, which are commonly known as unstable shoes (US). However, physiological responses during walking in US, particularly at various speeds, have not been extensively studied to date. The purpose of this study was to investigate the effect of wearing unstable shoes while walking at low to high speeds on the rate of perceived exertion (RPE), muscle activation, oxygen consumption (VO₂), and optimum speed. Healthy male adults wore US or normal walking shoes (WS), and walked at various speeds on a treadmill with no inclination. In experiment 1, subjects walked at 3, 4, 5, 6, and 7 km·h^-1 (duration, 3 min for all speeds) and were recorded on video from the right sagittal plane to calculate the step length and cadence. Simultaneously, electromyogram (EMG) was recorded from six different thigh and calf muscles, and the integrated EMG (iEMG) was calculated. In experiment 2, RPE, heart rate and VO₂ were measured with the walking speed being increased from 3.6 to 7.2 km·h^-1 incrementally by 0.9 km·h^-1 every 6 min. The optimum speed, defined by the least oxygen cost, was calculated from the fitted quadratic relationship between walking speed and oxygen cost. Wearing US resulted in significantly longer step length and lower cadence compared with WS condition at any given speed. For all speeds, iEMG in the medial gastrocnemius and soleus muscles, heart rate, and VO₂ were significantly higher in US than WS. However, RPE and optimum speed (US, 4.75 ± 0.32 km·h^-1; WS, 4. 79 ± 0.18 km·h^-1) did not differ significantly between the two conditions. These results suggest that unstable shoes can increase muscle activity of lower legs and energy cost without influencing RPE and optimum speed during walking at various speeds.

Key points

• During walking at various speeds, wearing unstable shoes results in longer step length and lower cadence compared with wearing WS.
• Wearing unstable shoes increases muscle activities of lower leg.
• Wearing unstable shoes shifts the quadratic relationship between walking speed and oxygen cost upward and increases energy cost about 4% without changes in RPE and optimum speed.

Key words: Rocker sole shoes, oxygen consumption, EMG, RPE, optimum speed     

Higher Cardiorespiratory Fitness in Older Trained Women is Due to Preserved Stroke Volume

Previous literature has shown that sedentary older women rely on peripheral adaptations to improve cardiorespiratory fitness with endurance training i.e. they show minimal increases in central parameters (cardiac output, Q) in response to endurance training. The purpose of this study therefore was to determine whether endurance trained older women were able to preserve maximal exercise Q and were characterized by a high stroke volume (SV) when compared to physically inactive older women. Trained (n = 7) and untrained (n = 1 0) women attended two maximal and one submaximal laboratory session. Breath-by-breath analysis was conducted using mass spectrometry and Q was assessed using acetylene open circuit inert gas wash-in. Multivariate analysis of variance and paired samples t-tests were used to determine between and within group differences. Trained women had a significantly higher VO_2max (37.5 vs. 24.1 ml^-1·kg·min^-1) compared to untrained women. There were no differences for peripheral oxygen extraction (VO₂/Q) at either submaximal or maximal work rates; however trained women had a significantly higher SV at maximal (119.3 vs. 94.6 ml) exercise compared to untrained women. In both trained and untrained women, SV did not rise significantly between submaximal and maximal exercise. Conclusion: Highly fit, endurance trained older women are able to preserve central parameters of VO_2max. Peripheral oxygen extraction is similar between older trained and untrained women.

Key points

• Older women are able to preserve stroke volume with high volumes of endurance training.
• Stroke volume of endurance trained older women does not continue to rise until maximal exercise, as is the case in young endurance trained adults.
• Peripheral oxygen extraction does not differ between endurance trained and physically inactive older women.

Key words: cardiac output, aging, exercise, running, VO_2max     

The Impact of Short Term Supervised and Home-Based Walking Programmes on Heart Rate Variability in Patients with Peripheral Arterial Disease

The aims of the study were to determine whether heart rate variability (HRV) measured at rest and during exercise could be altered by an exercise training programme designed to increase walking performance in patients with peripheral arterial disease. Forty-four volunteers were randomised into 12 weeks of either: supervised walking training twice weekly for 30 min at 75% VO_2peak (SU), home-based walking training sessions: twice weekly, 30 min per week (HB) or no exercise (CT). HRV measures were calculated from a 5-min resting ECG. Each patient then underwent maximal, graded exercise treadmill testing. All measures were repeated after 12 weeks. The SU group showed significantly (p < 0.001) increased maximal walking time (MWT) but no change in VO_2peak. There were no statistically significant changes in any of the measures of HRV in any group. Effect sizes for change in HRV measures were all very small and in some cases negative. Improved walking performance was not accompanied by central cardiorespiratory or neuroregulatory adaptations in the present study. The lack of any change in HRV was possibly due to either the low intensity or discontinuous nature of exercise undertaken.

Key points

• It is known that exercise can positively influence heart rate variability in some cardiac patients.
• It is known that exercise can increase walking performance in peripheral vascular disease patients.
• Exercise training improved walking performance in peripheral vascular disease patients but HRV was unaltered.
• This may be due to low overall physiological demands on the cardiovascular system or the intermittent nature of the exercise.

Key words: Exercise, ischemia, autonomic nervous system     

A Pilot Study to Investigate Explosive Leg Extensor Power and Walking Performance After Stroke

We examined explosive leg extensor power (LEP) and gait in men and women after a stroke using an experimental observational design. A convenience sample of consecutively referred individuals (8 men, 6 women) with chronic stroke mean age ± SD, range, 46.4 ± 8.4, 32 - 57 years, and able to walk for four minutes were recruited. The test re-test reliability and performance of LEP was measured together with walking parameters. LEP (Watts·kg^-1) and gait measures during a four-minute walk; temporal-spatial gait parameters (GAITRite^®) and oxygen cost of walking (mL·kg^-1·m^-1) were recorded. Percentage Asymmetry LEP (stronger LEP - weaker LEP/stronger LEP x 100) was calculated for each person. LEP was reliable from test to re-test ICC [3, 1] 0.8 - 0.7 (n = 9). Greater Asymmetry LEP correlated strongly with reduced walking velocity, cadence, stance time, and swing time on the weaker leg (n = 14) (p < 0.01). Findings demonstrate explosive LEP, in particular Percentage Asymmetry LEP, can be measured after stroke and is both reliable and related to walking performance. LEP training of the stronger or weaker leg warrants further investigation in this group.

Key Points

• Explosive leg power (LEP) is a reliable measure in individuals recovering from a stroke.
• Significant asymmetry occurred in LEP in this group.
• Greater LEP asymmetry related to reduced walking performance after stroke.

Key words: Stroke, leg extensor power, walking, asymmetry     

Oxygen Cost During Treadmill Walking with Hip and Knee Immobilised

The aim of this study was to determine the effect of immobilising the knee and hip on the oxygen cost (ml·kg^-1·min^-1) to velocity relationship during treadmill walking. The study was a prospective experimental conducted in a Rehabilitation centre. Ten healthy individuals, five men and five women, with no gait abnormality participated. Following familiarisation five men and five women walked on a treadmill and selected their own, free “comfortable walking velocity ”(SSWS). Subjects then performed an incremental test at -60 to +60% of SSWS. Individuals later repeated the test with the knee and hip of one limb immobilised. Samples of expired air were measured at each velocity and the oxygen cost (ml·kg^-1·min^-1) to Froude number (Fr) relationship plotted (where calculation of Fr normalizes for subjects of differing leg length and acts as an index of velocity). There was a higher oxygen cost, and lower Fr at SSWS during immobilised (0.21 ± 0.03 ml·kg^-1·min^-1; Fr = 0.12 ± 0. 03) compared with free walking (0.16 ± 0.02 ml·kg^-1·min^-1; Fr = 0.18 ± 0.04) (p < 0. 01). Statistical analysis demonstrated that during immobilised walking an inverse fit (y = β₀ + β₁/x) and for free walking a cubic fit (y = β₀ + β₁x + β₂x² + β₃x³) best fitted the data. Hip and knee immobilisation increased the oxygen cost at SSWS and altered the oxygen cost to Fr relationship. The results have implications in selecting optimal walking velocities in individuals with impairments affecting mobility such as hemiplegic gait.

Key Points

• Walking with one limb immobilised requires greater energy cost than normal free walking.
• This has clinical implications when developing rehabilitation strategies for patients who mobility problems such as those with hemi paretic gait.

Key words: Froude number, oxygen cost, immobilisation, hip, knee, walking, hemiplegic gait     

Measuring Oxygen Cost During Level Walking in Individuals with Acquired Brain Injury in the Clinical Setting

This study examined the test-retest reliability of oxygen cost (ml·kg^-1·min^-1) during level walking in individuals with acquired brain injury (ABI). Ten individuals with ABI (5 men, 5 women) (Traumatic brain injury, 1, central pontine myelinolysis, 1, stroke 8) and 21 healthy controls (11 men, 10 women). Measurements of gross and net (walking minus resting) oxygen consumption (ml·kg^-1·min^-1), and oxygen cost (ml·kg^-1·min^-1) during level walking at self-selected speeds. Measurements were taken on two occasions within one week. Oxygen cost was significantly lower (p < 0.05) in individuals with ABI on the second test versus the first test. Percentage variability in oxygen cost from test to re-test ranged from 14.7 to 17.3% in the control group and from 17.4 to 20.8% in the brain injury group. Clinical populations may demonstrate a significant decrease in oxygen cost between testing occasions. Individuals require at least one period of familiarisation if oxygen cost is used as an outcome measure during level walking in clinical groups. The amount of familiarisation has yet to be investigated in individuals with ABI.

Key Points

Individuals with brain injury during level walking

• May demonstrate a significant decrease in oxygen cost between testing occasions.
• May require at least one period of familiarisation if oxygen cost is used as an outcome measure
• The degree of familiarisation required in this clinical group needs further investigation

Key Words: Oxygen consumption brain injury, test re-test, level walking     

Physical Fitness and Serum Vitamin D and Cognition in Elderly Koreans

Poor physical fitness and low serum vitamin D are known to be modifiable risk factors for cognitive declines with normal aging. We investigated the association of physical fitness and serum vitamin D levels with global cognitive function in older adults. In this cross-sectional study, a total of 412 older Korean adults (108 men aged 74.4 ± 6.0 years and 304 women aged 73.1 ± 5.4 years) completed the Korean version of Mini-Mental State Examination (MMSE) to assess global cognitive performance and the senior fitness test to assess strength, flexibility, agility, and endurance domains of physical fitness. Body mass index, percent body fat, serum vitamin D, geriatric depression scale (GDS), level of education, smoking, and history of cardiovascular or cerebrovascular disease were also assessed as covariates. Age, sex, GDS, and body fatness were negatively associated with MMSE-based cognitive performance. Serum vitamin D and physical fitness were positively associated with MMSE-based cognitive performance. Multivariate linear regression showed that agility (partial R² = -0.184, p = 0.029) and endurance (partial R² = 0.191, p = 0.022) domains of physical fitness along with serum vitamin D (partial R² = 0.210, p = 0.012) were significant predictors for global cognitive performance after controlling for covariates (i.e., age, sex, education, GDS, body fatness, and comorbidity index). The current findings of the study suggest that promotion of physical fitness and vitamin D supplementation should be key components of interventions to prevent cognitive decline with normal aging.

Key points

• Cognitive declines are associated with normal aging as well as modifiable lifestyle risk factors, and there is an increasing need to identify the modifiable risk factors for the onset of cognitive declines and to provide evidence-based strategies for healthy and successful aging.
• In Korea, little is known about the relationships of physical fitness and serum vitamin D with cognitive function in older adults, and we determined the associations between a) serum vitamin D levels and cognitive function and b) physical fitness and cognitive function among community-dwelling elderly Koreans.
• The current findings of the study suggest that agility and endurance domains of physical fitness along with serum vitamin D were significant predictors for global cognitive performance after controlling for covariates.

Key words: Cognitive function, geriatrics, physical fitness, vitamin D     

Effects of Different Resistance Exercise Protocols on Nitric Oxide,Lipid Peroxidation and Creatine Kinase Activity in Sedentary Males

The purpose of this study was to determine the changes of oxidative response and exercise-induced muscle damage after two different resistance exercise protocols. Whether training with low or high intensity resistance programs cause alterations in the activities of lipid peroxidation, nitric oxide (NO_x), and creatine kinase (CK) activity in human plasma was investigated. Twenty untrained males participated into this study. Ten of the subjects performed high intensity resistance (HR) exercise circuit and the rest of them performed low intensity resistance (LR) exercise circuit of 4 different exercises as a single bout. Venous blood samples were drawn pre-exercise, immediately after the exercise, and at the 6^th, 24^th, 48^th and the72^nd hours of post-exercise. Samples were analyzed for markers of muscle damage (CK), lipid peroxidation (MDA) and NO_x. NO_x production increased in HR group (p < 0.05). The MDA response to the two different resistance exercise protocol in this study caused a significant increase between pre and post-exercise values in both groups (p < 0.05). Also, there was a significant difference in the MDA level between the two groups in post-exercise values (p < 0.05) and higher values were observed in HR group. CK activities showed a significant increase in all post exercise values (p < 0.05) of both groups but there were no difference between HR and LR groups. These findings support that high intensity resistance exercise induces free radical production more than low intensity resistance exercise program.

Key points

• High intensity resistance exercise caused increases in NO_x, MDA and CK levels.
• Light intensity resistance exercises increased MDA and CK levels but did not affect NO_x levels.
• Damage arose during resistance exercises may be related to the level of resistance applied.

Key words: Anaerobic, intensity, lipid peroxidation, damage, blood