The aims of this study were: to compare energy expenditure (EE) estimated from the existing GT3X accelerometer equations and EE measured with indirect calorimetry; to define new equations for EE ...estimation with the GT3X in youth, adults and older people; and to define GT3X vector magnitude (VM) cut points allowing to classify PA intensity in the aforementioned age-groups. The study comprised 31 youth, 31 adults and 35 older people. Participants wore the GT3X (setup: 1-s epoch) over their right hip during 6 conditions of 10-min duration each: resting, treadmill walking/running at 3, 5, 7, and 9 km · h⁻¹, and repeated sit-stands (30 times · min⁻¹). The GT3X proved to be a good tool to predict EE in youth and adults (able to discriminate between the aforementioned conditions), but not in the elderly. We defined the following equations: for all age-groups combined, EE (METs)=2.7406+0.00056 · VM activity counts (counts · min⁻¹)-0.008542 · age (years)-0.01380 · body mass (kg); for youth, METs=1.546618+0.000658 · VM activity counts (counts · min⁻¹); for adults, METs=2.8323+0.00054 · VM activity counts (counts · min⁻¹)-0.059123 · body mass (kg)+1.4410 · gender (women=1, men=2); and for the elderly, METs=2.5878+0.00047 · VM activity counts (counts · min⁻¹)-0.6453 · gender (women=1, men=2). Activity counts derived from the VM yielded a more accurate EE estimation than those derived from the Y-axis. The GT3X represents a step forward in triaxial technology estimating EE. However, age-specific equations must be used to ensure the correct use of this device.
Different pacing profiles have been identified in the literature for endurance sporting events: the 'positive', 'negative', 'even', 'parabolic shaped' and 'variable pacing'. Most studies have focused ...on competitive or elite athletes (including winners) without considering more recreational runners, for many of whom the primary goal is simply to finish the event. The major city marathons provide a large heterogeneous sample to compare the pacing profiles of competitive vs. recreational runners, and thus to understand pacing more broadly. A total of 190,228 New York finishers' (69,316 women) marathon times (from 2006 to 2011) were assessed. Although all runners developed a positive pace profile, a lower variability of speed through the race was found in the top runners (coefficient of variation (CV) for speed during 5-km splits: 7.8% (men) and 6.6% (women)) compared with the less successful runners (CV ranging from 8.3 to 14.4%). Both men and women try to maintain an even pace profile along the marathon course, partly by avoiding an excessively fast start that might result in a pronounced decrease in the speed in the second half of the race.
To determine whether 10 weeks of whole‐body vibration (WBV) training has a significant effect on strength, muscle mass, muscle power, and mobility in older women, 26 subjects were randomly assigned ...to a WBV training group (n=13; mean age 79 years) and a control (CON) group (n=13; mean age 76 years). Maximal voluntary isometric contraction (MVIC) increased 38.8% in the WBV group, without changes in the CON group. Electromyographic activity of the vastus medialis (VM), the vastus lateralis, and the biceps femoris (BF) did not change in either group. Thigh muscle cross‐sectional area increased significantly after training in VM (8.7%) and BF (15.5%). Muscle power at 20%, 40%, and 60% MVIC decreased from pre‐test to post‐test in the CON group; however, WBV training prevented the decrease in the WBV group. Consequently, mobility, measured by the Timed Up and Go test, increased significantly after training (9.0%) only in the WBV group. Ten weeks of lower limb WBV training in older women produces a significant increase in muscle strength induced by thigh muscle hypertrophy, with no change in muscle power. The adaptations to WBV found in the present study may be of use in counteracting the loss of muscle strength and mobility associated with age‐induced sarcopenia.
Intermonitor variability of GT3X accelerometer Santos-Lozano, A; Torres-Luque, G; Marín, P J ...
International journal of sports medicine,
12/2012, Letnik:
33, Številka:
12
Journal Article
Recenzirano
The main purpose of this study was to assess the inter-monitor reliability of the tri-axial GT3X Actigraph accelerometer over a range of physical activities (PA). This device collects motion data on ...each of the vertical (Y), horizontal right-left (X), and horizontal front-back (Z) axes and also calculates the vector summed value √X(2)+Y(2)+Z(2) known as 'vector magnitude' (VM). 8 GT3X accelerometers were worn at the same time by the same participant. Accelerometers were placed back-to-front, all facing forward and in sets of 4 securely taped together, attached to a belt and allocating each block above either left or right hip at waist level. Inter-monitor reliability was assessed during 6 conditions: rest, walking (4 and 6 km·h(-1)), running (8 and 10 km·h(-1)) and repeated sit-to-stand (40 times·min(-1)). The intra-class correlation coefficients were high for X, Y and Z axes (i.e., all ≥ 0.925) and for VM (≥ 0.946). In conclusion, we found good inter-instrument reliability of the GT3X accelerometer across all planes, yet our results also suggest that the X and Z axes do not provide further benefits over the 'traditional' Y-axis to assess the movement in typical PA.
Regular physical activity (PA) decreases mortality risk in survivors of breast and colorectal cancer. Such impacts of exercise have prompted initiatives designed both to promote and adequately ...monitor PA in cancer survivors. This study examines the validity of 2 widely used self-report methods for PA determination, the International Physical Activity Questionnaire short version (IPAQ-SF) and Global Physical Activity Questionnaire (GPAQ). Both instruments were compared with the triaxial accelerometry (Actigraph) method as an objective reference standard. Study participants were 204 cancer survivors (both sexes, aged 18-79 years). Compared with accelerometry, both questionnaires significantly overestimated PA levels (across all intensities) and underestimated physical inactivity levels. No differences were detected between the 2 questionnaires except for a shorter inactivity time estimated by GPAQ (
=0.001). The Bland and Altman method confirmed that both questionnaires overestimated all PA levels. Receiver operating characteristic (ROC) analysis classified IPAQ and GPAQ as fair and poor predictors, respectively, of the proportions of survivors fulfilling international PA recommendations (≥150 min·week
of moderate-vigorous PA). IPAQ-SF showed a higher sensitivity but lower specificity than GPAQ. Our data do not support the use of IPAQ-SF or GPAQ to determine PA or inactivity levels in cancer survivors.
Intensive muscular activity can trigger oxidative stress, and free radicals may hence be generated by working skeletal muscle. The role of the enzyme xanthine oxidase as a generating source of free ...radicals is well documented and therefore is involved in the skeletal muscle damage as well as in the potential transient cardiovascular damage induced by high-intensity physical exercise. Allopurinol is a purine hypoxanthine-based structural analog and a well-known inhibitor of xanthine oxidase. The administration of the xanthine oxidase inhibitor allopurinol may hence be regarded as promising, safe, and an economic strategy to decrease transient skeletal muscle damage (as well as heart damage, when occurring) in top-level athletes when administered before a competition or a particularly high-intensity training session. Although continuous administration of allopurinol in high-level athletes is not recommended due to its possible role in hampering training-induced adaptations, the drug might be useful in non-athletes. Exertional rhabdomyolysis is the most common form of rhabdomyolysis and affects individuals participating in a type of intense exercise to which they are not accustomed. This condition can cause exercise-related myoglobinuria, thus increasing the risk of acute renal failure and is also associated with sickle cell trait. In this manuscript, we have reviewed the recent evidence about the effects of allopurinol on exercise-induced muscle damage. More research is needed to determine whether allopurinol may be useful for preventing not only exertional rhabdomyolysis and acute renal damage but also skeletal muscle wasting in critical illness as well as in immobilized, bedridden, sarcopenic or cachectic patients.
Abstract Waldenström macroglobulinemia (WM) is a malignant lymphoproliferative disorder characterized by the presence of a high level of serum monoclonal IgM and a lymphoplasmacytic infiltrate in the ...bone marrow. This meta-analysis sought to assess the effectiveness of the different treatments for WM tested in published trials using the response rate (RR) as the main outcome measure. Forty-six articles (1409 patients) identified were entered in a variable effects model meta-analysis of proportions (rates and sample sizes). A greater response to treatment was produced in patients treated with a combination of 2+ drugs (RR = 73%; 95%CI: 62, 83; p < 0.01) than in those receiving monotherapy with rituximab (RR = 44%; 95%CI: 34, 55; p < 0.01) or a purine analogue 61% (95%CI: 43, 78; p < 0.01) for cladribine and 53% (95%CI: 34, 72; p < 0.01) for fludarabine. The combination rituximab + cladribine emerged as particularly effective (RR = 87%; 95%CI: 78, 94; p < 0.01), slightly more effective than rituximab + bortezomib/dexamethasone (RR = 84%; 95%CI: 79, 88; p < 0.01) and rituximab + cyclophosphamide/dexamethasone RR = 81% (95%CI: 72, 88; p < 0.01). Our results are in overall agreement with treatment recommendations from the seventh International Workshops on WM. Our findings are limited by the fact that we could not analyze progression-free survival (PFS). More phase II/III trials are needed to corroborate promising recent findings with bendamustine and carfilzomib and further research are needed to standardize recommendations based on maximum treatment efficacy combined with lowest toxicity, differentiation between first vs second line treatment, or long-term follow up after treatment.
The purpose of this review is to address methodological issues related to accelerometer-based assessments of physical activity (PA) in older individuals. Special interest is also put on recently ...updated technology. No definitive evidence exists currently to indicate which are the more valid and reliable accelerometer models for use with older people. When it comes to selecting an accelerometer, issues of affordability, product reliability, monitor size, technical support, and comparability with other studies may be equally as important as the relative validity and reliability of an instrument. The accelerometer should be attached as close as possible to the body's center of mass, and in the case of elders using walking aids, it should be placed on the same body side. Variability due to positioning can be reduced with careful training and supervision. Typically, the sampling period is between 3 and 7 days and it is not yet clear if variability exists between weekdays and weekend in the elderly. It is possible that aging effects on physical and cognitive health may limit the ability of an older adult to be compliant with an accelerometer protocol; in this line many methods have been suggested for increasing compliance to protocols for research studies. Accelerometers can provide reliable information on mobility and objective measurement of PA. These activity monitors have significant advantages when compared with other quantitative methods for measurement of energy expenditure. Accelerometers are currently used mainly in a research setting; however, with recent advances, incorporation into clinical and fitness practice is possible and increasing.
This study aims to examine the association between proliferator‐activated receptor γ (PGC)‐gene family‐related single nucleotide polymorphisms (SNPs) and elite endurance runners' status in a Chinese ...cohort, and to gain insights into the functionality of a subset of SNPs. Genotype distributions of 133 SNPs in PPARGC1A, PPARGC1B, PPRC1, TFAM, TFB1M, TFB2M, NRF1, GABPA, GABPB1, ERRα, and SIRT1 genes were compared between 235 elite Chinese (Han) endurance runners (127 women) and 504 healthy non‐athletic controls (237 women). Luciferase gene reporter activity was determined in 20 SNPs. After adjusting for multiple comparisons (in which threshold P‐value was set at 0.00041), no significant differences were found in allele/genotype frequencies between athletes and controls (when both sexes were analyzed either together or separately). The lowest P‐value was found in PPARGC1A rs4697425 (P = 0.001 for the comparison of allele frequencies between elite female endurance runners and their gender‐matched controls). However, no association (all P > 0.05) was observed for this SNP in a replication cohort from Poland (194 endurance athletes and 190 controls). Using functional genomics tool, the following SNPs were found to have functional significance: PPARGC1A rs6821591, rs12650562, rs12374310, rs4697425, rs13113110, and rs4452416; PPARGC1B rs251466 and rs17110586; and PPRC1 rs17114388 (all P < 0.001). This study found no significant association between PGC‐related SNPs and elite endurance athlete status in the Chinese population, despite some SNPs showing potential functional significance and the strong biological rationale to hypothesize that this gene pathway is a candidate to influence endurance exercise capacity.
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