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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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Sae Young Jae, Kevin Heffernan, Bo Fernhall and Yoon-Ho Choi

Background:

We tested the hypothesis that higher levels of cardiorespiratory fitness are inversely associated with carotid artery intima media thickness in 746 (age 53 ± 7 yrs) men with type 2 diabetes.

Methods:

We measured common carotid intima media thickness and defined carotid atherosclerosis as a carotid intima media thickness > 1.0 mm. Cardiorespiratory fitness was directly measured by peak oxygen uptake using expired gases analysis during a standard treadmill test.

Results:

Cardiorespiratory fitness was independently associated with common carotid intima media thickness in multivariable regression (β = –0.15, P < .05). After adjusting for established risk factors, high and moderate cardiorespiratory fitness were associated with lower odds ratios for having carotid atherosclerosis—0.49 (95% CI, 0.30–0.81), and 0.59 (95% CI, 0.38–0.92), respectively—as compared with low cardiorespiratory fitness. Each 1 metabolic equivalent increment higher cardiorespiratory fitness was associated with 27% (OR = 0.73; 95% CI, 0.61–0.87) lower prevalence of carotid atherosclerosis.

Conclusions:

These results suggest that high cardiorespiratory fitness is inversely associated with common carotid intima media thickness in men with type 2 diabetes.

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Meaghan Nolan, J. Ross Mitchell and Patricia K. Doyle-Baker

Background:

The popularity of smartphones has led researchers to ask if they can replace traditional tools for assessing free-living physical activity. Our purpose was to establish proof-of-concept that a smartphone could record acceleration during physical activity, and those data could be modeled to predict activity type (walking or running), speed (km·h−1), and energy expenditure (METs).

Methods:

An application to record and e-mail accelerations was developed for the Apple iPhone®/iPod Touch®. Twentyfive healthy adults performed treadmill walking (4.0 km·h−1 to 7.2 km·h1) and running (8.1 km·h−1 to 11.3 km·h−1) wearing the device. Criterion energy expenditure measurements were collected via metabolic cart.

Results:

Activity type was classified with 99% accuracy. Speed was predicted with a bias of 0.02 km·h−1 (SEE: 0.57 km·h−1) for walking, –0.03 km·h−1 (SEE: 1.02 km·h−1) for running. Energy expenditure was predicted with a bias of 0.35 METs (SEE: 0.75 METs) for walking, –0.43 METs (SEE: 1.24 METs) for running.

Conclusion:

Our results suggest that an iPhone/iPod Touch can predict aspects of locomotion with accuracy similar to other accelerometer-based tools. Future studies may leverage this and the additional features of smartphones to improve data collection and compliance.

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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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Elaine A. Rose and Gaynor Parfitt

Using a mixed-method approach, the aim of this study was to explore affective responses to exercise at intensities below-lactate threshold (LT), at-LT, and above-LT to test the proposals of the dual-mode model (Ekkekakis, 2003). These intensities were also contrasted with a self-selected intensity. Further, the factors that influenced the generation of those affective responses were explored. Nineteen women completed 20 min of treadmill exercise at each intensity. Affective valence and activation were measured, pre-, during and postexercise. Afterward, participants were asked why they had felt the way they had during each intensity. Results supported hypotheses showing affect to be least positive during the above-LT condition and most positive during the self-selected and below-LT conditions. Individual differences were greatest in the below-LT and at-LT conditions. Qualitative results showed that factors relating to perceptions of ability, interpretation of exercise intensity, exercise outcomes, focus of concentration, and perceptions of control influenced the affective response and contributed to the individual differences shown in the quantitative data.

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Ehsan Ghahramanloo, Adrian W. Midgley and David J. Bentley

Background:

There is little information regarding the effects of concurrent training (endurance and resistance training performed in the same overall regimen) on blood lipid profile in sedentary male subjects. This study compared the effects of 3 different 8-wk training programs [endurance training (ET), strength training (ST) and concurrent training (CT)] on blood lipid profile and body composition in untrained young men.

Methods:

A total of 27 subjects were randomly allocated to an ET, ST or CT group which performed either progressive treadmill (ET), free weight (ST) or both the endurance and strength training requirements for 8 weeks.

Results:

High-density lipoprotein and low-density lipoprotein profiles significantly improved in the ET and CT groups (P < .01) but not in the ST group. Triglyceride and total cholesterol profiles significantly improved in all 3 training groups. Total fat mass significantly decreased in the ET and CT groups (P < .001) but not in the ST group, whereas fat free mass significantly increased in the ST and CT groups (P < .01) but not in the ET group.

Conclusions:

These results indicate that CT can be used to simultaneously improve both the serum lipid profile and body composition of previously untrained, apparently health young men.

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Jamie L. Moul, Bert Goldman and Beverly Warren

The effect of exercise on cognitive performance in an older population was studied. Thirty sedentary men and women 65–72 years of age were randomly assigned to a walking group, a weight training group, or a placebo control group. Intervention groups exercised 30–60 min 5 days per week for 16 weeks, with the walking group training at 60% heart rate reserve, the weight training group employing the DAPRE method of weight progression, and the placebo control group engaging in mild range-of-motion and flexibility movements that kept their heart rates close to resting levels. At baseline and 16 weeks posttraining each subject completed the Ross Information Processing Assessment (RIPA), a maximal graded treadmill test, and a strength assessment of the knee extensors and elbow flexors. Sixteen weeks of walking improved VO2peak of the sedentary subjects 15.8%; VO2peak did not improve in the other two groups. Additionally, the RIPA scores of the walking group increased 7.5%, while those of the weight-training and control groups showed little change.

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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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Shannon J. FitzGerald, Carolyn E. Barlow, James B. Kampert, James R. Morrow Jr., Allen W. Jackson and Steven N. Blair

Background:

The beneficial effects of cardiorespiratory fitness on mortality are well known; however, the relation of muscular fitness, specifically muscular strength and endurance, to mortality risk has not been thoroughly examined. The purpose of the current study is to determine if a dose-response relation exists between muscular fitness and mortality after controlling for factors such as age and cardiorespiratory fitness.

Methods:

The study included 9105 men and women, 20–82 years of age, in the Aerobics Center Longitudinal Study who have completed at least one medical examination at the Cooper Clinic in Dallas, TX between 1981 and 1989. The exam included a muscular fitness assessment, based on 1-min sit-up and 1-repetition maximal leg and bench press scores, and a maximal treadmill test. We conducted mortality follow-up through 1996 primarily using the National Death Index, with a total follow-up of 106,046 person-years. All-cause mortality rates were examined across low, moderate, and high muscular fitness strata.

Results:

Mortality was confirmed in 194 of 9105 participants (2.1%). The age- and sex-adjusted mortality rate of those in the lowest muscular fitness category was higher than that of those in the moderate fitness category (26.8 vs. 15.3 per 10,000 person-years, respectively). Those in the high fitness category had a mortality rate of 20.6 per 10,000 person-years. The moderate and high muscular fitness groups had relative risks of 0.64 (95%CI = 0.44–0.93) and 0.80 (95%CI = 0.49–1.31), adjusting for age, health status, body mass index, cigarette smoking, and cardio-respiratory fitness when compared with the low muscular fitness group.

Conclusions:

Mortality rates were lower for individuals with moderate/high muscular fitness compared to individuals with low muscular fitness. These findings warrant further research to confirm the apparent threshold effect between low and moderate/high muscular fitness and all-cause mortality.

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Katja Krustrup Pedersen, Esben Lykke Skovgaard, Ryan Larsen, Mikkel Stengaard, Søren Sørensen and Kristian Overgaard

individuals. Finally, most validation studies are carried out in laboratory-based settings, which allows for good control of type, speed, and intensity of the activities performed. However, extrapolating data from treadmill to overground walking and running for use in free-living activity research requires