Effects of Exercise Intervention on Habitual Physical Activity Above Lactate Threshold Under Free-living Conditions: A Randomized Controlled Trial.

The purpose of the present investigation was to examine the effects of an exercise-based intervention on the daily physical activity (PA) above the lactate threshold under free-living conditions. A total of 81 middle-aged to older males (51±7 years) were randomly assigned into one of 2 groups. The subjects' body weight, visceral fat area, lactate threshold (LT), and PA levels were measured before and after the 8-week lifestyle intervention. The PA levels were assessed using a pedometer with a uni-axial accelerometer (Lifecorder, Kenz, Nagoya). During the intervention, 300 min/week of exercise at LT was targeted in the exercise group. The LT was determined by the log-log transformation method. The subjects in the control group were instructed to maintain their usual lifestyles. In the exercise group, the body weight, visceral fat area and LT significantly improved after the intervention. In contrast, the duration of PA at an intensity of LT, >3 METs and >6 METs did not differ significantly. The present investigation did not find significant changes in the PA at LT under free-living conditions as a result of an 8-week exercise-based intervention, although the participants successfully improved their aerobic capacity and body composition.

Objectively measured physical activity levels of Venetian adults.

AIM: Venice, Italy, provides a unique environment to study physical activity as there are no automobiles, and walking is the most common means of transportation. The purpose of the present investigation was to objectively assess the physical activity (PA) levels of residents in Venice, Italy, using an accelerometer. METHODS: Twenty-seven Venetians (12 men and 15 women, 48 ± 16 yr, 169.4 ± 6.6 cm, 71.7 ± 11.1 kg) had worn an accelerometer (Lifecorder Ex) for 7 consecutive days in order to determine daily number of steps, time spent in light (LPA), moderate (MPA), or vigorous intensity (VPA) and moderate to vigorous intensity (MVPA) as well as energy expenditure associated with PA (PAEE). The time for all PA and MVPA lasting at least 1 minute, 3 minutes, 5 minutes and 10 minutes were also assessed. RESULTS: The PAEE, number of steps, LPA, MPA, VPA and MVPA averaged over 7 days of week were 1575 ± 524 kJ∙day⁻¹, 11920 ± 3667 steps∙day⁻¹, 77 ± 23 min∙day 43 ± 19 min∙day⁻¹, and 45 ± 21 min∙day⁻¹. The time for MVPA lasting >10 min was 0.3 ± 0.9 min∙day⁻¹. CONCLUSION: The amount and intensity of PA in Venetian adults is substantially higher than in most other populations previously evaluated, particularly American adults. The effects of the highly active Venetian lifestyle on important health outcomes remain unclear, but warrant further investigation.

Accumulation of short bouts of non-exercise daily physical activity is associated with lower visceral fat in Japanese female adults.

The purpose of the present investigation was to assess the relationship between bouts of very short daily physical activity (PA) lasting <10 min with obesity and abnormal fat distributions. A total of 42 females (age 50±6 years, height 156±5 cm, body weight 54±8 kg, body mass index 22±3 kg/m2) participated in the present investigation. Computed tomography was used to evaluate the area of visceral adipose tissue and subcutaneous adipose tissue (VAT and SAT). All participants wore a pedometer with a one-axial accelerometer (Lifecorder, Kenz, Japan) in order to determine their frequency (bouts/day) of PA and moderate to vigorous intensity PA (MVPA). The total frequency of PA and MVPA, including all bout durations, was not significantly associated with the body fat distribution. The frequency of PA lasting longer than 3 min and 5 min, and MVPA lasting longer than 1 min and 3 min were significantly associated with the area of the VAT (p<0.05). A smaller area of VAT was associated with a higher frequency of PA and MVPA lasting 1-5 min. The present investigation did not find that very short bouts of PA lasting<1 min played a significant role in controlling abdominal fat distribution.

Are pedometers adequate instruments for assessing energy expenditure?

OBJECTIVE: Assessing energy expenditure (EE) is important for the control of obesity. Daily step counts have become popular and constitute one practical technique for evaluating the physical activity (PA) in large population studies. However, information on the capacity of pedometers to track EE in free-living conditions remains scanty. SUBJECTS AND METHODS: The 24-h EE of 71 healthy adults was measured by indirect calorimetry in a large respiratory chamber. Two accelerometers were attached to the waist, one for counting the total daily steps (ACC(STEP)) and another for measuring the anteroposterior whole body acceleration calculated as the root mean square of the acceleration signal at every second (ACC(RMS)). RESULTS: The ACC(STEP) was not associated with PA-related EE (PAEE) or 24-h EE. Body weight (BW) was the main determinant of both the values (explaining 30 and 75% of the variance, respectively). Approximately 8% (P<0.001) of the variance in PAEE was attributed to the ACC(RMS) after BW was accounted for, whereas the ACC(STEP) did not explain any additional variance. A multiple stepwise regression analysis revealed that BW, height and ACC(RMS) were highly significant determinants of 24-h EE and accounted for as much as 83% of the total variance. CONCLUSIONS: Recording the number of steps per day does not provide accurate information on EE, and at best is only a crude predictor of the general PA in terms of displacement. In contrast, accelerometry signals are considered to be a more meaningful factor in the assessment of EE rather than step counts under sedentary conditions.

Daily physical activity assessment: what is the importance of upper limb movements vs whole body movements?

OBJECTIVE: The movement of the upper limbs (eg fidgeting-like activities) is a meaningful component of nonexercise activity thermogenesis (NEAT). This study examined the relationship between upper limb movements and whole body trunk movements, by simultaneously measuring energy expenditure during the course of the day. DESIGN: A cross-sectional study consisting of 88 subjects with a wide range in body mass index (17.3-32.5 kg/m(2)). The energy expenditure over a 24-h period was measured in a large respiratory chamber. The body movements were assessed by two uniaxial-accelerometers during daytime, one on the waist and the other on the dominant arm. The accelerometry scores from level 0 (=immobile) up to level 9 (=maximal intensity) were recorded. The activities of subjects were classified into eight categories: walking at two speeds on a horizontal treadmill (A & B), ambling (C), self-care tasks (D), desk work (E), meals (F), reading (G), watching TV (H). RESULTS: There was a significant relationship between the accelerometry scores from the waist (ACwaist) and that from the wrist (ACwrist) over the daytime period (R(2)=0.64; P<0.001). The ACwrist was systematically higher than the ACwaist during sedentary activities, whereas it was the reverse for walking activities. ACwrist to ACwaist ratio of activities E-H were above 1.0 and for walking activities (A-C) were below 1.0. A multiple regression analysis for predicting daytime energy expenditure revealed that the explained variance improved by 2% only when the ACwrist was added as a second predictor in addition to the ACwaist. This indicates that the effect of the ACwrist for predicting energy expenditure was of limited importance in our conditions of measurement. CONCLUSIONS: The acceleration of the upper limbs which includes fidgeting is more elevated than that of the whole body for sitting/lying down activities. However, their contribution to energy expenditure is lower than whole body trunk movements, thus indicating that the weight-bearing locomotion activities may be a key component of NEAT. However, its contribution may depend on the total duration of the upper limb movements during the course of the day.

Constriction of a fused operon consisting of the recA and kan (kanamycin resistance) genes and regulation of its expression by the lexA gene.

The kanamycin resistance gene (kan) of transposon Tn5 was cloned into a derivative of plasmid pBR322. A DNA fragment containing the promoter-operator region of the recA gene was inserted into the promoter region of the cloned kan gene to produce a fused operon, recA-kan. Plasmid pMCR685 carrying recA-kan expressed a low level of activity of the kan gene product (kanamycin phosphotransferase; KPT) in the wild-type cells of Escherichia coli, while the plasmid showed an increased level of the activity in the SPr- mutant cells which produce the inactive lexA protein. The KPT activity in the wild-type cells harboring the plasmid increased 6- to 11-fold upon treatment of the cells with mitomycin C or nalidixic acid, both of which are known to induce synthesis of recA protein. Expression of the recA-kan operon fusion was remarkably repressed by the lexA gene cloned into a plasmid carrying the operon fusion. Higher concentrations of mitomycin C were required for maximal induction of KPT activity in the cells harboring the resulting plasmid pMCR687. These results strongly suggest that the lexA gene product can be itself repress the recA gene, and that pMCR687 is a useful vector to clone genes whose expression is harmful to the host cell growth.