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Carmelo Bazzano, Lee N. Cunningham, Giovanni Cama and Tony Falconio

This study examined the physiology of the 1-mile walk test as administered in the field with 16 (7 M, 9 F) older adults (mean age 66.1 ± 5.9 yrs). Physiologic data were obtained via a Cosmed K2 miniaturized O2 analyzer with telemetric capabilities during a maximal treadmill (TM) test and a 1-mile walk test (MWT). Oxygen consumption (ml · kg−1 · min−1), minute ventilation (L · min−1), and heart rate (b · min−1) values obtained at maximal levels on the TM were 25.6 ± 7.6, 57 ± 17, and 155 ± 16, respectively. The measured V̇O2 submax during the MWT was 18.5 + 5, V̇E submax was 44 ± 10, and HR submax was 140 ± 19. The subjects were able to hold 74% of the V̇O2max, 81% of V̇Emax, and 91% of HR max. An upward drift for HR and V̇E was noted while V̇O2 remained constant throughout the MWT. The MWT with older subjects requires a vigorous level of metabolic and cardiorespiratory intensity. For healthy older adults who have been properly screened for hidden metabolic and cardiovascular diseases, participation in the MWT appears feasible.

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Candace D. Perkins, James M. Pivarnik and Matthew R. Green

Background:

The reliability and validity of the SensorMedics VmaxST was tested.

Methods:

Thirty subjects (age = 24.5 ± 4.0 years, height = 174.8 ± 9.8 cm, weight = 70.3 ± 12.6 kg) performed treadmill exercise on three occasions, twice using the VmaxST and once using the SensorMedics 2900 system. Oxygen consumption (VO2; L/min) and heart rate (HR; beats/min) were measured continuously during three, 6- minute stages: 80 m/min, 0% grade; 94 m/min, 5% grade; and 160 m/min, 0% grade, and VO2max.

Results:

Reliability was high, and measurement error was low for VO2 (Rxx range = 0.97 - 0.99, CI = 0.94 - 1.00, SEM = 0.03 - 0.08 L/min) and HR (Rxx = 0.94 - 0.99, CI = 0.88 - 1.00, SEM = 1.8 - 3.2 beats/min). Validity was high for VO2 (Rxy range = 0.92 - 0.98, CI = 0.84 - 0.99, SEE = 0.08 - 0.21 L/min) and HR (Rxy = 0.97 - 0.99, CI = 0.94 - 1.00, SEE = 0.9 - 1.8 beats/min). Mean differences in VO2 between VmaxST and 2900 were small yet significant (P < 0.001).

Conclusions:

The VmaxST demonstrated excellent reliability and validity for measuring VO2 and HR over several exercise intensities. Small overestimates in VO2 by the VmaxST are countered by low measurement error.

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Michael R.M. McGuigan, Roger Bronks, Robert U. Newton, John C. Graham and David V. Cody

Peripheral arterial disease (PAD) is associated with impaired lower extremity function. This study investigated differences in PAD and control participants and the relationship between lower limb strength and clinical measures of PAD severity. Participants were evaluated by 6-min-walk distance, normal and maximal walking speed over 10 m, isometric plantar-flexion strength, and dynamic dorsi-/plantar-flexion strength. Hemodynamic measures of the lower limbs were recorded at rest and after maximal treadmill testing. PAD participants walked significantly less far during the 6-min walk, and there were large differences in normal and maximal walking speeds. Small to moderate differences were found for isometric plantar-flexion strength. In the diseased legs of the PAD participants, resting systolic hallux photoplethysmography was significantly correlated with isokinetic plantar-flexion strength and onset of claudication pain during the 6-min-walk test. In addition to confirming the documented loss of walking endurance, these data suggest that loss of strength of the plantar flexors is associated with increasing PAD impairment.

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Andréa L. Maslow, Anna E. Price, Xuemei Sui, Duck-chul Lee, Ikka Vuori and Steven N. Blair

Background:

This study examined the associations of body mass index (BMI), waist circumference (WC), and cardiorespiratory fitness (CRF) with incident functional limitation (IFL) in adults.

Methods:

Patients (n = 2400), 30+ years [mean age, 45.2 (SD, 8.3); 12% women], completed a baseline health examination during 1979 to 1995. CRF was quantified by age-and sex-specific thirds for maximal treadmill exercise test duration. Adiposity was assessed by BMI and WC (grouped for analysis according to clinical guidelines). Incident IFL was identified from mail-back surveys during 1995, 1999, and 2004.

Results:

After adjusting for potential confounders and either BMI or WC, CRF was inversely related to IFL (P trend < .001). The association between BMI and IFL was significant after adjusting for all confounders (P trend = .002), but not after additional adjustment for CRF (P trend = .23). After controlling for all confounders and CRF, high WC was associated with greater odds of IFL in those aged 30 to 49; normal WC was associated with greater odds of IFL in those aged 50+.

Conclusions:

CRF was a significant predictor of IFL in middle aged and older adults, independent of overall or abdominal adiposity. Clinicians should consider the importance of preserving functional capacity by recommending regular physical activity for normal-weight and overweight individuals.

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Gianluca Vernillo, Aldo Savoldelli, Barbara Pellegrini and Federico Schena

Background:

Accurate assessments of physical activity and energy expenditure (EE) are needed to advance research on positive and negative graded walking.

Purpose:

To evaluate the validity of 2 SenseWear Armband monitors (Pro3 and the recently released Mini) during graded walking.

Methods:

Twenty healthy adults wore both monitors during randomized walking activities on a motorized treadmill at 7 grades (0%, ±5%, ±15%, and ±25%). Estimates of total EE from the monitors were computed using different algorithms and compared with values derived from indirect calorimetry methodology using a 2-way mixed model ANOVA (Device × Condition), correlation analyses and Bland-Altman plots.

Results:

There was no significant difference in EE between the 2 armbands in any of the conditions examined. Significant main effects for device and condition, as well as a consistent bias, were observed during positive and negative graded walking with a greater over- and under-estimation at higher slope.

Conclusions:

Both the armbands produced similar EE values and seem to be not accurate in estimation of EE during activities involving uphill and downhill walking. Additional work is needed to understand factors contributing to this discrepancy and to improve the ability of these monitors to accurately measure EE during graded walking.

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Charles F. Morgan, Allison R. Tsuchida, Michael William Beets, Ronald K. Hetzler and Christopher D. Stickley

Background:

Physical activity guidelines for youth and adults include recommendations for moderate intensity activity to attain health benefits. Indirect calorimetry studies have consistently reported a 100 ste·min−1 threshold for moderate intensity walking in adults. No indirect calorimetry studies have investigated step-rate thresholds in children and therefore the primary purpose of the study was to determine preliminary step-rate thresholds for moderate physical activity walking in children.

Methods:

Oxygen consumption was measured at rest and used to determine 3 and 4 age-adjusted metabolic equivalents (A-AMETs) for 4 treadmill trials (self-selected, 2.5, 3.0, and 3.5 MPH). Two trained observers simultaneously counted children’s steps during each walking trial. Step-rate thresholds associated with moderate-intensity activity, defined as 3 and 4 A-AMETs, were determined using hierarchical linear modeling.

Results:

Regression analysis determined an overall step rate of 112 and 134 step·min-1 for 3 and 4 A-AMETs respectively. Body mass index (BMI) weight status and age were positively related to A-AMETs.

Conclusions:

We suggest age and BMI weight status specific recommendations that range from a low of 100 step·min-1 threshold (3 A-AMETs) for overweight/obese 11- to 12-year-olds to a high of 140 step·min-1 threshold (4 A-AMETs) for healthy weight 9- to 10-year-old children.

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Rebecca E. Hasson, Kirsten E. Granados, David Xavier Marquez, Gary Bennett, Patty Freedson and Barry Braun

Background:

Racial differences in psychological determinants of exercise exist between non-Hispanic blacks (blacks) and non-Hispanic whites (whites). To date, no study has examined racial differences in the psychological responses during and after exercise. The objective of this study was to compare psychological outcomes of single exercise bouts in blacks and whites.

Methods:

On 3 separate occasions, sedentary black (n = 16) and white (n = 14) participants walked on a treadmill at 75%max HR for 75 minutes. Questionnaires assessing mood, state anxiety, and exercise task self-efficacy were administered before and after each exercise bout. In-task mood and rating of perceived exertion (RPE) were measured every 5 minutes during exercise.

Results:

Exercise self-efficacy and psychological distress significantly improved in both blacks and whites. However during exercise blacks reported more positive in-task mood and lower RPE compared with whites.

Conclusions:

These data suggest that racial differences exist in psychological responses during exercise. Further research should confirm these findings in a larger, free-living population.

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Amy L. Nikolai, Brittany A. Novotny, Cortney L. Bohnen, Kathryn M. Schleis and Lance C. Dalleck

Background:

The purposes of this study were (1) to assess the cardiovascular and metabolic responses to water aerobic exercise and (2) to determine if water aerobics exercise meets the American College of Sports Medicine (ACSM) guidelines for improving and maintaining car-diorespiratory fitness.

Methods:

Fourteen men and women—mean ± SD age 57.4 ± 7.6 y, height 171.3 ± 7.8 cm, weight 89.9 ± 13.9 kg, body-fat percentage 32.5% ± 5.8%, and maximal oxygen uptake (VO2max) 31.0 ± 8.3 mL · kg−1 · min−1—completed a maximal treadmill exercise test and a 50-min water aerobics session. Cardiovascular and metabolic data were collected via a portable calorimetric measurement system.

Results:

Mean exercise intensity was 43.4% of heart-rate reserve and 42.2% of maximal oxygen uptake reserve. Training intensity in metabolic equivalents was 4.26 ± 0.96. Total net energy expenditure for the exercise session was 249.1 ± 94.5 kcal/session.

Conclusions:

Results indicate that water aerobics is a feasible alternative to land-based exercise for middle-aged and older adults that fulfills the ACSM guidelines for improving and maintaining cardiorespiratory fitness.

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James J. McClain, Teresa L. Hart, Renee S. Getz and Catrine Tudor-Locke

Background:

This study evaluated the utility of several lower cost physical activity (PA) assessment instruments for detecting PA volume (steps) and intensity (time in MVPA or activity time) using convergent methods of assessment.

Methods:

Participants included 26 adults (9 male) age 27.3 ± 7.1 years with a BMI of 23.8 ± 2.8 kg/m2. Instruments evaluated included the Omron HJ-151 (OM), New Lifestyles NL-1000 (NL), Walk4Life W4L Pro (W4L), and ActiGraph GT1M (AG). Participants wore all instruments during a laboratory phase, consisting of 10 single minute treadmill walking bouts ranging in speed from 40 to 112 m/min, and immediate following the laboratory phase and during the remainder of their free-living day (11.3 ± 1.5 hours). Previously validated AG MVPA cutpoints were used for comparison with OM, NL, and W4L MVPA or activity time outputs during the laboratory and free-living phase.

Results:

OM and NL produced similar MVPA estimates during free-living to commonly used AG walking cutpoints, and W4L activity time estimates were similar to one AG lifestyle cutpoint evaluated.

Conclusion:

Current findings indicate that the OM, NL, and W4L, ranging in price from $15 to $49, can provide reasonable estimates of free-living MVPA or activity time in comparison with a range of AG walking and lifestyle cutpoints.

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Neha Singhal and Anupa Siddhu

Background:

The relationship between leisure-time physical activity (LTPA) and cardiorespiratory fitness (CRF) is not clearly understood in Indian men. It is important to elucidate whether the duration or intensity of LTPA is responsible for increasing CRF. This will help in designing better physical activity intervention strategies for improving CRF in Indian men.

Methods:

Healthy nondiabetic urban Indian men with no history of coronary heart disease (CHD) were selected (n = 603; aged 22–64 years) and their energy intake and physical activity was determined using a questionnaire. Body fat (percent) was determined by leg-to-leg bioelectrical impedance analysis while CRF was measured on multistage, continuous treadmill test using Bruce protocol.

Results:

Intensity of physical activity (METs) emerged as the best independent predictor of CRF (β = 0.217; P < .001). Using univariate General Linear Model, it was found that CRF is more a function of LTPA intensity than LTPA duration, since LTPA duration was not related to CRF when controlled for LTPA intensity. However, LTPA intensity remained significantly associated with CRF even after adjustment for LTPA duration.

Conclusion:

LTPA of preferably higher intensity should be incorporated in the lifestyle to improve CRF and prevent CHD in Indian men.