The metabolic equivalents of one-mile walking by older adults; implications for health promotion.

Background: Instructions for older adults regarding the intensity of walking may not elicit an intensity to infer health gains. We recorded the metabolic equivalents (METs) during a 1-mile walk using constant and predicted values of resting MET in older adults to establish walking guidelines for health promotion and participation. Methods: In a cross-sectional design study, participants (15 men, 10 women) walked 1-mile overground, in a wooden floored gymnasium, wearing the Cosmed K4b2 for measurement of energy expenditure. Constant or predicted values for resting MET were used to calculate the number of 1-mile walks to meet 450-750 MET∙min∙wk-1. Results: Participants had MET values higher than 3 for both methods, with 29% and 64% of the participants higher than 6 for a constant and predicted MET value, respectively. The METs of the1-mile walk were (mean ± SD) 6 ± 1 and 7 ± 1 METs using constant and predicted resting MET,and similar for men (constant: 6 ± 1 METs; predicted: 7 ± 1 METs) and women (constant: 5±1METs; predicted: 6 ± 1 METs) (P > 0.05). Conclusion: Older adults that are instructed to walk 1-mile at a fast and constant pace meet the minimum required intensity for physical activity, and public health guidelines. Health professionals, that administer exercise, could encourage older adults to accumulate between six and nine 1-mile walks per week for health gains.

Blackcurrant Alters Physiological Responses and Femoral Artery Diameter during Sustained Isometric Contraction.

Blackcurrant is rich in anthocyanins that may affect exercise-induced physiological responses. We examined tissue oxygen saturation, muscle activity, cardiovascular responses and femoral artery diameter during a submaximal sustained isometric contraction. In a randomised, double-blind, crossover design, healthy men (n = 13, age: 25 ± 4 years, BMI: 25 ± 3 kg·m-2, mean ± SD) ingested New Zealand blackcurrant (NZBC) extract (600 mg∙day-1 CurraNZ™) or placebo (PL) for 7-days separated by 14-days washout. Participants produced isometric maximal voluntary contractions (iMVC) and a 120-s 30%iMVC of the quadriceps with electromyography (EMG), near-infrared spectroscopy, hemodynamic and ultrasound recordings. There was no effect of NZBC extract on iMVC (NZBC: 654 ± 73, PL: 650 ± 78 N). During the 30%iMVC with NZBC extract, total peripheral resistance, systolic, diastolic, and mean arterial pressure were lower with increased cardiac output and stroke volume. With NZBC extract, EMG root mean square of the vastusmedialis and muscle oxygen saturation were lower with higher total haemoglobin. During the 30%iMVC, femoral artery diameter was increased with NZBC extract at 30 (6.9%), 60 (8.2%), 90 (7.7%) and 120 s (6.0%). Intake of NZBC extract for 7-days altered cardiovascular responses, muscle oxygen saturation, muscle activity and femoral artery diameter during a 120-s 30%iMVC of the quadriceps. The present study provides insight into the potential mechanisms for enhanced exercise performance with intake of blackcurrant.

Dose effects of New Zealand blackcurrant on substrate oxidation and physiological responses during prolonged cycling.

PURPOSE: It has been previously shown that New Zealand blackcurrant (NZBC) extract increased fat oxidation during short duration cycling. The present study examined the effect of different doses of NZBC extract on substrate oxidation and physiological responses during prolonged cycling. METHODS: Using a randomized counterbalanced Latin-square design, 15 endurance-trained male cyclists (age: 38 ± 12 years, height: 187 ± 5 cm, body mass: 76 ± 10 kg, [Formula: see text]: 56 ± 8 mL kg-1 min-1, and mean ± SD) completed four separate 120-min cycling bouts at 65% [Formula: see text] after ingesting no dose, or one of three doses (300, 600, or 900 mg day-1) of NZBC extract (CurraNZ™) for 7 days. RESULTS: A dose effect (P < 0.05) was observed for average fat oxidation (0, 300, 600, and 900 mg day-1 values of 0.63 ± 0.21, 0.70 ± 0.17, 0.73 ± 0.19, and 0.73 ± 0.14 g min-1) and carbohydrate oxidation (0, 300, 600, and 900 mg day-1 values of 1.78 ± 0.51, 1.65 ± 0.48, 1.57 ± 0.44, and 1.56 ± 0.50 g min-1). The individual percentage change of mean fat oxidation was 21.5 and 24.1% for 600 and 900 mg day-1 NZBC extract, respectively, compared to no dose. Heart rate, [Formula: see text], [Formula: see text], plasma lactate, and glucose were not affected. CONCLUSION: Seven-day intake of New Zealand blackcurrant extract demonstrated a dose-dependent effect on increasing fat oxidation during 120-min cycling at 65% [Formula: see text] in endurance-trained male cyclists.

Cardiovascular function during supine rest in endurance-trained males with New Zealand blackcurrant: a dose-response study.

PURPOSE: Blackcurrant contains anthocyanins that could alter cardiovascular function and reduce cardiovascular disease risk. We examined dose responses of New Zealand blackcurrant (NZBC) extract on cardiovascular function during supine rest. METHODS: Fifteen endurance-trained male cyclists (age: 38 ± 12 years, height: 178 ± 5 cm, body mass: 76 ± 10 kg, [Formula: see text]: 56 ± 8 mL kg-1 min-1, mean ± SD) were randomly assigned using a counterbalanced Latin square design to complete four conditions, a control of no NZBC, or one of three doses (300, 600 or 900 mg day-1) of NZBC extract (CurraNZ™) for 7-days with a 14-day washout. Cardiovascular function (i.e., blood pressure, heart rate, ejection time, cardiac output, stroke volume, and total peripheral resistance) during supine rest was examined (Portapres® Model 2). RESULTS: Systolic and diastolic blood pressure, heart rate and ejection time were unchanged by NZBC. A dose effect (P < 0.05) was observed for cardiac output, stroke volume, and total peripheral resistance. A trend for a dose effect was observed for mean arterial blood pressure. Cardiac output increased by 0.6 ± 0.6 L min-1 (15%) and 1.0 ± 1.0 L min-1 (28%) and stroke volume by 5 ± 8 mL (7%) and 6 ± 17 mL (18%) between control and 600, and 900 mg day-1, respectively. Total peripheral resistance decreased by 4 ± 3 mmHg L-1 min-1 (20%) and 5 ± 9 mmHg L-1 min-1 (20%) for 600, and 900 mg day-1. CONCLUSION: Seven-days intake of New Zealand blackcurrant extract demonstrated dose-dependent changes on some cardiovascular parameters during supine rest in endurance-trained male cyclists.

Beneficial Physiological Effects With Blackcurrant Intake in Endurance Athletes.

Blackcurrant contains anthocyanins, known to influence vasorelaxation and peripheral blood flow. We examined the effects of 7 days intake of Sujon New Zealand blackcurrant powder (6g/day) on the lactate curve, maximum oxygen uptake, and cardiovascular responses at rest and during cycling. Thirteen trained triathletes with >3 yrs experience (8 men, age: 38 ± 8 yrs, body mass: 71 ± 9 kg, BF%: 19 ± 5%, mean ± SD) performed two incremental cycling protocols with recording of physiological and cardiovascular responses (Portapres Model 2). Cardiovascular function was also measured in rest. Experimental design was double-blind, placebo-controlled, randomized and cross-over (wash-out 4 wks). Data were analyzed with two-tailed t tests and 2-way ANOVA and significance accepted at p < .05. Plasma lactate was lower at 40%, 50%, 60% and 70% of maximum power by 27%, 22%, 17% and 13%. Intensity at 4 mmol · La(-1) OBLA was 6% higher with blackcurrant without effect on heart rate and oxygen uptake. Maximum values of oxygen uptake, heart rate and power were not affected by blackcurrant, but obtained with 14% lower lactate. In rest, blackcurrant increased stroke volume and cardiac output by 25% and 26%, and decreased total peripheral resistance by 16%, with no changes in blood pressure and heart rate. Cardiovascular responses during exercise at 40%, 50%, 60%, 70% and 80% intensity were not affected. Sujon New Zealand blackcurrant powder affects lactate production and/or clearance during exercise. Sujon New Zealand blackcurrant powder affects physiological and cardiovascular responses in rest and during exercise that may have implications for exercise performance.

Isometric strength and steadiness adaptations of the knee extensor muscles to level and downhill treadmill walking in older adults.

An ageing related decline in muscle strength and steadiness decreases quality of life and increases the risk for falls. Downhill treadmill walking (DTW) may enhance muscle strength and steadiness in older adults. Eighteen healthy older adults (age: 67 ± 4, body mass: 75 ± 14 kg) completed 12-weeks of level treadmill walking (LTW, 0 %, n = 8) or DTW (-10 %, n = 10) (30 min, 3 days per week) at a self-selected walking speed (re-adjusted in week 4 and 8). Maximal voluntary isometric force (MVIF) and electromyography (EMG) of the m. quadriceps femoris (QF) were measured at baseline, 4, 8 and 12 weeks. Steadiness of submaximal (5, 10 and 20 % MVIF) isometric contractions (i.e. coefficient of variation of the force signal) and EMG of QF were measured at baseline and 12 weeks. Baseline MVIF of LTW (340 ± 112 N) and DTW (368 ± 128 N) increased equally by 14 ± 6 and 5 ± 6 % (p < 0.05). Steadiness at 5 %MVIF improved following 12 weeks of LTW (baseline: 0.04 ± 0.01; 12 weeks: 0.03 ± 0.01) and DTW (baseline: 0.04 ± 0.02; 12 weeks: 0.03 ± 0.01 (p < 0.05). EMG root mean square of m. vastus lateralis during MVIF increased by 38 % following 12 weeks of LTW only (p < 0.05). The potential implications for an exercise modality, such as DTW, with a lower oxygen demand, to improve muscle strength could serve as a rehabilitative countermeasure for older adults.

Functional mobility of older adults after concentric and eccentric endurance exercise.

Age-associated decline in muscle mass and strength impairs functional mobility in older adults. We examined the effects of an eccentric endurance exercise programme (downhill treadmill walking, DTW) at a self-selected walking speed (SSWS) on functional mobility and eccentric and concentric strength of m. quadriceps femoris of older adults. Twenty-four older adults (67 ± 4 years) were randomly assigned to complete 3 × 30 min treadmill walks per week for 12 weeks on a level (n = 11, LTW 0%) or downhill (n = 13, DTW -10%) treadmill gradient at SSWS. SSWS was re-adjusted every 4 weeks. Participants were assessed for five repetition sit-to-stand (5-RSTS), maximal walking speed (MWS), timed up-and-go (TUG) and dynamic strength. SSWS was similar for both groups with increases from 1.18 ± 0.11 to 1.53 ± 0.09 m s(-1) (LTW) and 1.26 ± 0.16 to 1.61 ± 0.12 m s(-1) (DTW) (time, P < 0.01). Improvements in 5-RSTS, MWS and TUG were substantial and similar for both groups (time, P < 0.01). 5-RSTS (baseline LTW: 8.50 ± 1.19 s, DTW: 8.54 ± 1.52 s) improved by 32 and 34%. MWS (baseline LTW: 2.39 ± 0.38 m s(-1), DTW: 2.40 ± 0.33 m s(-1)) improved by 22 and 23%. TUG (baseline LTW: 5.58 ± 0.51 s, DTW: 5.46 ± 0.89 s) improved by 22% for both groups. Peak eccentric and concentric torque did not change. Knee angle of concentric peak torque (180° s(-1)) was decreased after 12 weeks in both groups (LTW: 37° ± 16° to 26° ± 14°, DTW: 42° ± 18° to 37° ± 16°, P < 0.05). Regular level and downhill treadmill walking by older adults, at a SSWS, results in substantial improvements in functional mobility. Changes in functional mobility were not explained by changes in dynamic strength of the m. quadriceps femoris.