Alejandro Santos-Lozano

Actigraph GT3X: Validation and Determination of Physical Activity Intensity Cut Points

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.

Technical variability of the GT3X accelerometer

To analyze the intra- and inter-instrument reliability of the ActiGraph GT3X accelerometer using a vibration table on each orthogonal axis and at five frequencies of motion. Ten GT3X units were subjected to a specific vibration using a motorized vibration table along the vertical, horizontal right-left and horizontal front-back axis, and at 1.1, 2.1, 3.1, 4.1 and 10.2 Hz. The 5 min data for each frequency were analyzed separately for frequency, axis effects, and inter- and intra-instrument variability. We found overall high intra-and inter-instrument reliability for the GT3X accelerometer at frequencies between 2.1 and 4.1 Hz. For frequencies ranging between 2.1 and 4.1 Hz, the intra-instrument coefficient of variation was ≤2.5%. The inter-instrument coefficient of variation ranged widely along axes and frequencies, with the lowest values (≤9%) corresponding to 2.1-4.1 Hz. The intra-class correlation coefficient for activity counts across frequencies and for all axes was 0.97. Overall, our findings support the use of the GT3X accelerometer as an accurate tool to estimate free-living physical activity, at least within those frequencies that are common to most types of human daily activities.

Exercise attenuates the major hallmarks of aging.

Regular exercise has multi-system anti-aging effects. Here we summarize how exercise impacts the major hallmarks of aging. We propose that, besides searching for novel pharmaceutical targets of the aging process, more research efforts should be devoted to gaining insights into the molecular mediators of the benefits of exercise and to implement effective exercise interventions for elderly people.

ApoE gene and exceptional longevity: Insights from three independent cohorts

The ApoE gene is associated with the risk of Alzheimer or cardiovascular disease but its influence on exceptional longevity (EL) is uncertain. Our primary purpose was to determine, using a case-control design, if the ApoE gene is associated with EL. We compared ApoE allele/genotype frequencies among the following cohorts: cases (centenarians, most with 1+ major disease condition; n=163, 100-111years) and healthy controls (n=1039, 20-85years) from Spain; disease-free cases (centenarians; n=79, 100-104years) and healthy controls (n=597, age 27-81years) from Italy; and cases (centenarians and semi-supercentenarians, most with 1+ major disease condition; n=729, 100-116years) and healthy controls (n=498, 23-59years) from Japan. Our main findings were twofold. First, the ε4-allele was negatively associated with EL in the three cohorts, with the following odds ratio (OR) values (adjusted by sex) having been found: 0.55 (95% confidence interval (CI): 0.33, 0.94), P=0.030 (Spain); 0.41 (95%CI: 0.18, 0.99), P=0.05 (Italy); and 0.35 (95%CI: 0.26, 0.57), P<0.001 (Japan). Second, although no association was found in the Spanish cohort (OR=1.42 (95%CI: 0.89, 2.26), P=0.145), the ε2-allele was positively associated with EL in the Italian (OR=2.14 (95%CI: 1.18, 3.45), P=0.01) and Japanese subjects (OR=1.81 (95%CI: 1.25, 2.63), P=0.002). Notwithstanding the limitations of case-control designs, our data suggest that the ApoE might be a candidate to influence EL. The ε4-allele appears to decrease the likelihood of reaching EL among individuals of different ethnic/geographic origins. An additional, novel finding of our study was that the ε2-allele might favor EL, at least in the Italian and Japanese cohorts.

Physical Inactivity and Low Fitness Deserve More Attention to Alter Cancer Risk and Prognosis

Sedentary lifestyle is associated with elevated cancer risk whereas regular physical activity (PA) and high cardiorespiratory fitness (CRF) have the opposite effect, with several biologic mechanisms mediating such associations. There is a need for lifestyle interventions aimed at increasing the PA levels and CRF of the general population and particularly cancer survivors. Furthermore, provocative data suggest a dose-dependent benefit of increasing levels of PA and/or CRF against cancer risk or mortality. Thus, current PA guidelines (≥150 min/wk of moderate-to-vigorous PA) may not be sufficiently rigorous for preventing cancer nor for extending cancer survivorship. Research targeting this issue is urgently needed. Promoting regular PA along with monitoring indicators of CRF and adiposity may provide powerful strategies to prevent cancer in populations, help patients with cancer more effectively deal with their disease and enhance secondary prevention programs in those who are affected by cancer. Cancer Prev Res; 8(2); 105–10. ©2014 AACR.

Validity of the ActivPAL™ and the ActiGraph monitors in preschoolers

PURPOSE This study aimed to compare three objective measures (GT1M ActiGraph, ActivPAL™, and direct observation) of sedentary behavior in preschoolers. METHODS Fifty-two 4- to 6-yr-old preschoolers wore an ActivPAL™ and a GT1M ActiGraph for five consecutive days and were videotaped for 1 h during classroom activities at preschool. The area under the receiver operating characteristic curve was calculated to assess the criterion validity of the ActivPAL™ (sitting/lying, with and without standing still) and the GT1M ActiGraph (<100 counts per minute) to estimate sedentary behavior (directly observed sitting behaviors). A two-way repeated-measures ANOVA was used to define the convergent validity of the ActivPAL™ and the GT1M ActiGraph sedentary behavior estimates across the measurement days. The practical utility of the ActivPAL™ was tested in the same sample by asking the parents how their child perceived wearing the ActivPAL™. RESULTS Results indicated a poor classification accuracy for both devices (area under the receiver operating characteristic curve, 0.6) to measure sedentary behavior based on the direct observation, with and without the inclusion of standing. Time defined as sedentary behavior (sitting/lying) was lower for the ActivPAL™ compared with the GT1M ActiGraph (mean bias, 7.7%; limits of agreement, -29.01% to 13.6%). According to the parental reports, 38% of the preschoolers had skin irritation due to wearing the ActivPAL™ for consecutive days. CONCLUSIONS Low classification accuracy was found for the ActivPAL™ and the GT1M ActiGraph to measure sedentary behavior in preschoolers. No correction factor can be suggested to make the sedentary estimates of the GT1M ActiGraph and the ActivPAL™ convergent as no systematic bias and wide limits of agreement were found. Furthermore, the practical utility of the ActivPAL™ was perceived to be lower compared with the ActiGraph accelerometer in preschoolers.

Whole-body vibration increases upper and lower body muscle activity in older adults: Potential use of vibration accessories

The current study examined the effects of whole-body vibration (WBV) on upper and lower body muscle activity during static muscle contractions (squat and bicep curls). The use of WBV accessories such as hand straps attached to the platform and a soft surface mat were also evaluated. Surface electromyography (sEMG) was measured for the medial gastrocnemius (MG), vastus lateralis (VL), and biceps brachii (BB) muscles in fourteen healthy older adults (74.8±4.5 years; mean±SD) with a WBV stimulus at an acceleration of 40 m s(-2) (30 Hz High, 2.5 mm or 46 Hz Low, 1.1 mm). WBV increased lower body (VL and MG) sEMG vs baseline (no WBV) though this was decreased with the use of the soft mat. The addition of the bicep curl with hand straps had no effect on lower body sEMG. WBV also increased BB sEMG vs baseline which was further increased when using the hand straps. There was no upper body effect of the soft mat. This study demonstrates WBV increases both lower and upper body muscle activity in healthy older adults. Moreover, WBV accessories such as hand straps attached to the platform or a soft surface mat may be used to alter exercise intensity.

A comparison of training intensity between whole-body vibration and conventional squat exercise

The aim of this study was to investigate surface electromyographic activity (sEMG) and rate of perceived exertion (RPE) during semi-squat exercise on vibration platform compared with semi-squat exercise performed on a Smith machine. Twenty-three recreationally active students (15 males and 8 females) were exposed to six different loads in one of both exercise modes: vibration or Smith machine. The subject performed a squat in six experimental conditions; the load differed per experimental condition. For each subject the exercise mode (n=2) and the different loads per mode (n=6) were assigned in a random order to check the influence of vibration magnitude (acceleration: ms(-2)) as well as weight (kg) on sEMG and RPE. Two-way ANOVA for RPE, lumbar and lower-body sEMG revealed a significant weight main effect (P<0.01) and a significant acceleration main effect (P<0.01). The results from this study demonstrate that the training stimulus resulting from an isometric semi-squat exercise on a vibration platform (acceleration: from 12 to 89 ms(-2)) is similar to the training stimulus of an isometric semi-squat exercise on Smith machine (weight: from 20 to 70 kg) according to lower-body sEMG and RPE. However, the impact of semi-squat on vibration platform exercise for lumbar muscle is relatively small compared with semi-squat on Smith machine.

Benefits of aerobic or resistance training during pregnancy on maternal health and perinatal outcomes: A systematic review

OBJECTIVE To understand what evidence exists with regard to maternal and offspring benefits of aerobic and/or resistance training during pregnancy. METHODS Systematic review of RCTs (published until May 2015) with healthy pregnant women and focusing on the benefits of exercise interventions on maternal health or perinatal outcomes. Studies were ranked as high/low quality, and a level of evidence was established according to the number of high-quality studies and consistency of the results. RESULTS 61 RCTs were analyzed. The evidence for a benefit of combined exercise [aerobic+resistance (muscle strength)] interventions on maternal cardiorespiratory fitness and prevention of urinary incontinence was strong. A weak or insufficient level of evidence was found for the rest of interventions and outcomes CONCLUSION The exercise modality that seems to induce a more favorable effect on maternal health is the combination of aerobic and resistance exercises during pregnancy.

ACTN3 R577X Polymorphism and Explosive Leg-Muscle Power in Elite Basketball Players

PURPOSE To determine the association of the ACTN3 R577X polymorphism with leg-muscle explosive power in Spanish (white) elite basketball players and controls. PARTICIPANTS 100 (60 men) elite basketball players (cases) and 283 nonathletic controls. METHODS The authors assessed power performance by means of the vertical-squat and countermovement-jump tests. RESULTS Genotype distributions did not differ between groups (cases: 37.0% [RR], 42.0% [RX], and 21.0% [XX]; controls: 31.8% [RR], 49.8% [RX], and 18.4% [XX]; P = .353). The authors did not observe any effect of the ACTN3 R577X polymorphism on study phenotypes in either group, including when they performed the analyses separately in men and women. They found no association between the ACTN3 R577X polymorphism and the likelihood of being an elite basketball player using the dominant or the recessive model, and the results remained unaltered when the analyses were adjusted for sex, weight, height, and age or when performed for men and women separately. CONCLUSIONS Although the ACTN3 R577X is associated with explosive muscle performance and this phenotype is important in the sport of basketball (ie, during jumps), the authors found no association with leg explosive power in elite basket players or with the status of being this type of athlete.