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Robin P. Shook, Nicole C. Gribben, Gregory A. Hand, Amanda E. Paluch, Gregory J. Welk, John M. Jakicic, Brent Hutto, Stephanie Burgess and Steven N. Blair

Background:

Subjective measures of moderate and vigorous physical activity (MVPA) rely on relative intensity whereas objective measures capture absolute intensity; thus, fit individuals and unfit individuals may perceive the same activity differently.

Methods:

Adults (N = 211) wore the SenseWear Armband (SWA) for 10 consecutive days to objectively assess sedentary time and MVPA. On day 8, participants completed the International Physical Activity Questionnaire (IPAQ) to subjectively assess sitting time and MVPA. Fitness was assessed via a maximal treadmill test, and participants were classified as unfit if the result was in the bottom tertile of the study population by sex or fit if in the upper 2 tertiles.

Results:

Overall, estimates of MVPA between the IPAQ and SWA were not significantly different (IPAQ minus SWA, 67.4 ± 919.1 MVPA min/wk, P = .29). However, unfit participants overestimated MVPA using the IPAQ by 37.3% (P = .02), but fit participants did not (P = .99). This between-group difference was due to overestimation, using the IPAQ, of moderate activity by 93.8 min/wk among the unfit individuals, but underestimation of moderate activity among the fit participants by 149.4 min/wk.

Conclusion:

Subjective measures of MVPA using the IPAQ varied by fitness category; unfit participants overestimated their MVPA and fit participants accurately estimated their MVPA.

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Kate Lyden, Sarah Kozey Keadle, John Staudenmayer, Patty Freedson and Sofiya Alhassan

Background:

The Compendium of Energy Expenditures for Youth assigns MET values to a wide range of activities. However, only 35% of activity MET values were derived from energy cost data measured in youth; the remaining activities were estimated from adult values.

Purpose:

To determine the energy cost of common activities performed by children and adolescents and compare these data to similar activities reported in the compendium.

Methods:

Thirty-two children (8−11 years old) and 28 adolescents (12−16 years) completed 4 locomotion activities on a treadmill (TRD) and 5 age-specific activities of daily living (ADL). Oxygen consumption was measured using a portable metabolic analyzer.

Results:

In children, measured METs were significantly lower than compendium METs for 3 activities [basketball, bike riding, and Wii tennis (1.1−3.5 METs lower)]. In adolescents, measured METs were significantly lower than compendium METs for 4 ADLs [basketball, bike riding, board games, and Wii tennis (0.3−2.5 METs lower)] and 3 TRDs [2.24 m·s-1, 1.56 m·s-1, and 1.34 m·s-1 (0.4−0.8 METs lower)].

Conclusion:

The Compendium of Energy Expenditures for Youth is an invaluable resource to applied researchers. Inclusion of empirically derived data would improve the validity of the Compendium of Energy Expenditures for Youth.

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Lauren Gulka, James Dziura and Loretta DiPietro

Background:

Little attention has been paid to the study of transient growth hormone (GH) responses to exercise in older women. We determined the effect of a single bout of exercise on GH in fit and unfit older (age 55 to 81 y; n = 19) and younger (age 18 to 25 y; n = 19) women.

Methods:

Exercise consisted of five 15-min intervals of treadmill exercise at 75% VO2peak. Blood samples were taken before, during, and following exercise for determination of plasma GH and insulin concentrations.

Results:

GH responses to exercise were attenuated in older compared with younger women (P < 0.01); however, these age differences were minimized in older age by fitness level. Adjusted area under the curve for GH was 5.50 and 1.76 µg/L · 102 for fit and unfit older women (P < 0.01), and 8.46 and 8.46 µg/L · 102 for fit and unfit younger women.

Conclusions:

Low levels of cardiorespiratory fitness in older women may require a greater relative exercise stimulus to augment meaningful GH responses.

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Benjamin J. Darter, Kathleen F. Janz, Michael L. Puthoff, Barbara Broffitt and David H. Nielsen

Background:

A new triaxial accelerometer (AMP 331) provides a novel approach to understanding free-living activity through its ability to measure real time speed, cadence, and step length. This study examined the reliability and accuracy of the AMP 331, along with construction of prediction equations for oxygen consumption and energy cost.

Methods:

Young adult volunteers (n = 41) wearing two AMP units walked and ran on a treadmill with energy cost data simultaneously collected through indirect calorimetry.

Results:

Statistically significant differences exist in inter-AMP unit reliability for speed and step length and in accuracy between the AMP units and criterion measures for speed, oxygen consumption, and energy cost. However, the differences in accuracy for speed were very small during walking (≤ 0.16 km/h) and not clinically relevant. Prediction equations constructed for walking oxygen uptake and energy expenditure demonstrated R 2 between 0.76 to 0.90 and between subject deviations were 1.53 mL O2 · kg-1 · min−1 and 0.43 kcal/min.

Conclusions:

In young adults, the AMP 331 is acceptable for monitoring walking speeds and the output can be used in predicting energy cost during walking but not running.

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Gina Bravo, Pierre Gauthier, Pierre-Michel Roy, Daniel Tessier, Philippe Gaulin, Marie-France Dubois and Lucie Péloquin

A battery of field tests was recently developed to assess five fitness parameters in elderly persons. The present study examined the test-retest reliability of each item in the battery and tested the validity of the cardiorespiratory endurance item. Reliability and validity data were obtained from two convenience samples. The 29 subjects in the reliability study were community-living women enrolled in seniors’ exercise classes. The validity of the cardiorespiratory endurance item was tested by comparing it with maximal work capacity on a treadmill test. The 52 women in that part of the study were all participants in a study to assess the effect of weight-bearing exercises on women with low bone mass. Both samples were combined for a principal component analysis. Low reproducibility was observed for coordination (0.54) and strength/endurance (0.56). After slightly modifying the test protocol for these two items, reproducibility reached 84 and 94%, respectively. The correlation between the cardiorespiratory endurance score and maximal work capacity was −0.65, while that between the composite score and maximal work capacity was −0.64. Given these minor modifications, then, the Functional Fitness Assessment battery is a reliable and valid tool for assessing functional fitness in elderly women.

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Patrick B. Wilson

Background:

Psoriasis confers risk for cardiometabolic disorders. Cardiorespiratory fitness is inversely associated with risk of cardiometabolic disorders in other populations, but limited data have been published assessing cardiorespiratory fitness among individuals with psoriasis. This investigation aimed to: 1) assess cardiorespiratory fitness among individuals with psoriasis in the general population; and 2) compare levels to individuals without psoriasis.

Methods:

A secondary data analysis from the 2003–2004 National Health and Nutritional Examination Survey was performed. Cardiorespiratory fitness was assessed with a treadmill test, while measures of psoriasis severity included rating of psoriasis as a life problem and body surface area involvement.

Results:

Twenty-six of 1093 participants reported a psoriasis diagnosis (population weighted prevalence 2.9%). Individuals with psoriasis had lower cardiorespiratory fitness compared with individuals without psoriasis (36.2 vs. 39.1 mL∙kg-1∙min-1, P = .009). No differences in self-reported or accelerometer physical activity were found by psoriasis diagnosis. Cardiorespiratory fitness was not significantly lower in those reporting high life impairment or body surface area involvement.

Conclusions:

Cardiorespiratory fitness may be lower in individuals with psoriasis and these differences may not be explained by self-reported disease severity measures or physical activity. Future studies should examine whether validated measures of psoriasis severity predict lower cardiorespiratory fitness.

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Marcos R. Kunzler, Emmanuel S. da Rocha, Maarten F. Bobbert, Jacques Duysens and Felipe P. Carpes

Background:

In negotiating stairs, low foot clearance increases the risk of tripping and a fall. Foot clearance may be related to physical fitness, which differs between active and sedentary participants, and be acutely affected by exercise. Impaired stair negotiation could be an acute response to exercise. Here we determined acute changes in foot clearances during stair walking in sedentary (n = 15) and physically active older adults (n = 15) after prolonged exercise.

Methods:

Kinematic data were acquired during negotiation with a 3-steps staircase while participants walked at preferred speed, before and after 30 min walking at preferred speed and using a treadmill. Foot clearances were compared before and after exercise and between the groups.

Results:

Sedentary older adults presented larger (0.5 cm for lead and 2 cm for trail leg) toe clearances in ascent, smaller (0.7 cm) heel clearance in the leading foot in descent, and larger (1 cm) heel clearance in the trailing foot in descent than physically active.

Conclusion:

Sedentary older adults negotiate stairs in a slightly different way than active older adults, and 30 min walking at preferred speed does not affect clearance in stair negotiation.

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Paul D. Loprinzi and Brandee Smith

Objective:

To use the most recent ActiGraph model (GT9X) to compare counts per minute (CPM) estimates between wrist-worn and waist-worn attachment sites.

Methods:

Participants completed 2 conditions (laboratory [N = 13] and free-living conditions [N = 9]), in which during both of these conditions they wore 2 ActiGraph GT9X accelerometers on their nondominant wrist (side-by-side) and 2 ActiGraph GT9X accelerometers on their right hip in line with the midaxillary line (side-by-side). During the laboratory visit, participants completed 5 treadmill-based trials all lasting 5 min: walk at 3 mph, 3.5 mph, 4 mph, and a jog at 6 mph and 6.5 mph. During the free-living setting, participants wore the monitors for 8 hours. Paired t test, Pearson correlation and Bland-Altman analyses were employed to evaluate agreement of CPM between the attachment sites.

Results:

Across all intensity levels and setting (laboratory and free-living), CPM were statistically significantly and substantively different between waist- and wrist-mounted accelerometry.

Conclusion:

Attachment site drastically influences CPM. As such, extreme caution should be exercised when comparing CPM estimates among studies employing different attachment site methodologies, particularly waist versus wrist.

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Fiona Iredale, Frank Bell and Myra Nimmo

Fourteen sedentary 50- to 55-year-old men were exercised to exhaustion using an incremental treadmill protocol. Mean (±SEM) peak oxygen uptake (V̇O2peak) was 40.5 ± 1.19 ml · kg1 · min−1, and maximum heart rate was 161 ± 4 beats · min−1. Blood lactate concentration was measured regularly to identify the lactate threshold (oxygen consumption at which blood lactate concentration begins to systematically increase). Threshold occurred at 84 ± 2% of V̇O2peak. The absolute lactate value at threshold was 2.9 ± 0.2 mmol · L−1. On a separate occasion, 6 subjects exercised continuously just below their individual lactate thresholds for 25 min without significantly raising their blood lactate levels from the 10th minute to the 25th. The absolute blood lactate level over the last 20 min of the steady-state test averaged 3.7 ± 1.2 mmol · L−1. This value is higher than that elicited at the threshold in the incremental test because of the differing nature of the protocols. It was concluded that although the lactate threshold occurs at a high percentage of V̇O2peak, subjects are still able to sustain exercise at that intensity for 25 min.

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Barbara E. Ainsworth, Robert G. McMurray and Susan K. Veazey

The purpose of this study was to determine the accuracy of two submaximal exercise tests, the Sitting-Chair Step Test (Smith & Gilligan. 1983) and the Modified Step Test (Amundsen, DeVahl, & Ellingham, 1989) to predict peak oxygen uptake (VO2 peak) in 28 adults ages 60 to 85 years. VO2 peak was measured by indirect calorimetry during a treadmill maximal graded exercise test (VO2 peak, range 11.6–31.1 ml · kg −l · min−1). In each of the submaximal tests, VO2 was predicted by plotting stage-by-stage submaximal heart rate (HR) and perceived exertion (RPE) data against VO2 for each stage and extrapolating the data to respective age-predicted maximal HR or RPE values. In the Sitting-Chair Step Test (n = 23), no significant differences were observed between measured and predicted VO2 peak values (p > .05). However, predicted VO2 peak values from the HR were 4.3 ml · kg−1 · min−1 higher than VO2 peak values predicted from the RPE data (p < .05). In the Modified Step Test (n = 22), no significant differences were observed between measured and predicted VO2 peak values (p > .05). Predictive accuracy was modest, explaining 49–78% of the variance in VO2 peak. These data suggest that the Sitting-Chair Step Test and the Modified Step Test have moderate validity in predicting VO2 peak in older men and women.