Light Intensity Exercise Research Articles

Differentiated Perceived Exertion and Self-Regulated Wheelchair Exercise

ObjectiveTo investigate the utility of the differentiated rating of perceived exertion (RPE) for the self-regulation of submaximal wheelchair propulsion in novice users. DesignEach participant completed a submaximal incremental test and a graded test to exhaustion to determine peak oxygen consumption (Vo2peak) on a wheelchair ergometer. On a separate day, two 12-minute intermittent bouts consisting of three 4-minute stages were completed at individualized imposed power outputs equating to light (40% Vo2peak) and moderate (60% Vo2peak) intensity exercise. On a third occasion, participants were assigned to either the overall group or the peripheral group and were required to self-regulate 12-minute intermittent exercise according to either overall RPE or peripheral RPE reported during the corresponding imposed intensity trial. SettingLaboratory facilities at a university. ParticipantsPreliminary population of able-bodied participants with no prior experience of wheelchair propulsion (N=18). InterventionsNot applicable. Main Outcome MeasuresDifferences in oxygen consumption (V˙o2), heart rate, blood lactate concentration, and power output between the imposed and self-regulated exercise trials. ResultsNo difference was found in physiological responses between the moderate-intensity imposed and RPE-regulated trials in the peripheral group, whereas a significant (P<.05) underproduction in V˙o2 (1.76±.31 vs 1.59±.25L/min) and blood lactate concentration (2.8±0.90 vs 2.21±.83mmol/L) was seen in the overall group. In contrast, a significant (P<.05) overproduction was seen in the peripheral group at a light exercise intensity, whereas no difference was found between all variables during the light-intensity imposed and RPE-regulated trials in the overall group. ConclusionsPeripheral RPE enabled a more precise self-regulation during moderate-intensity wheelchair exercise in novice users. In contrast, overall RPE provided a more accurate stimulus when performing light-intensity propulsion.

Another look at active rehabilitation for slow-to-recover sport-related concussion in children and adolescents: further evidence to support its effectiveness

ObjectiveTo explore and impact of a previously developed active rehabilitation intervention for children who are slow-to-recover after concussion.DesignProspective repeated measures design.SettingThe Montreal Children's Hospital Concussion Clinic.ParticipantsTen children (three girls and...

High Intensity Interval Training in Patients With Cardiovascular Disease: A Brief Review of Physiologic Adaptations and Suggestions for Future Research

High Intensity Interval Training in Patients With Cardiovascular Disease: A Brief Review of Physiologic Adaptations and Suggestions for Future Research

Relative Validity of 3 Accelerometer Models for Estimating Energy Expenditure During Light Activity

With physical inactivity inextricably linked to the increasing prevalence of obesity, there is a need for validated methods that measure free-living energy expenditure (EE) within sedentary environments. While accelerometers enable these measurements, few studies have compared device accuracy in such settings. The aim of this study was to investigate the relative validity of the Actigraph, RT3 and SenseWear Armband (SWA). Twenty-three (11 male, 12 female) participants (age: 25.3 ± 6.3 yr; BMI: 22.6 ± 2.7) wore 3 accelerometers at designated sites during a 4-hour stay in the Whole Room Calorimeter (WRC). Participants performed 2 10-minute bouts of light-intensity exercise (stepping and stationary cycling) and engaged in unstructured sedentary activities. EE estimated by accelerometers was compared with WRC EE derived from measurements of gaseous exchange. The Actigraph and SWA both accurately estimated EE during the stepping exercise. EE estimated by the RT3 during stepping was significantly lower than the WRC value (31.2% ± 15.6%, P < .001). All accelerometers underestimated cycling and unstructured activity EE over the trial period (P < .001). The Actigraph and SWA are both valid tools for quantifying EE during light-intensity stepping. These results provide further valuable information on how accelerometer devices may be appropriately used.

Subjective Measures of Exercise Intensity to Gauge Substrate Partitioning in Persons With Paraplegia

The Borg Rating of Perceived Exertion (RPE) Scale and talk test (TT) are commonly recommended for persons to gauge exercise intensity. It is not known whether they are suitable to estimate substrate partitioning between carbohydrate and fat in persons with SCI. Investigate substrate partitioning/utilization patterns associated with RPE and TT. Twelve participants with chronic paraplegia underwent 2 arm crank exercise tests on nonconsecutive days within 2 weeks. Test 1 was a graded exercise test (GXT) to volitional exhaustion. Test 2 was a 15-minute self-selected steady state (SS) voluntary arm exercise bout simulating a brief, yet typical exercise session. For the GXT, very light intensity exercise (RPE < 9) and TT stage before last positive were associated with highest contribution of fat oxidation (~35%-50%) to total energy expenditure (TEE). Fat oxidation was low at all stages, with the highest rate (0.13 ± 0.07 g/min) occurring at stage 1 (10 W). Corresponding average RPE was 7 ± 2 and the TT was positive for all participants at this stage. For the SS, fuel partitioning throughout exercise was dominated by carbohydrate oxidation (1.47 ± 0.08 g/min), accounting for almost all (~94%) of TEE with only a minute contribution from fat oxidation (0.02 ± 0.004 g/min). A positive TT was associated with an average contribution of fat oxidation of ~10%. RPE but not the TT appears suitable to predict exercise intensities associated with the highest levels of fat oxidation. However, such intensities are below authoritative intensity thresholds for cardiorespiratory fitness promotion, and therefore the applicability of such a prediction for exercise prescriptions is likely limited to individuals with low exercise tolerance.

Changes in calf muscle deoxygenation after foam sclerotherapy in patients with superficial venous insufficiency

This study assessed changes in the calf muscle deoxygenated hemoglobin (HHb) level during light-intensity exercise after ultrasound-guided foam sclerotherapy (UGFS) for superficial venous insufficiency. UGFS with 1% or 3% polidocanol foam (POL-F) was used to treat unilateral great saphenous vein reflux in 84 patients. Near-infrared spectroscopy (NIRS) was used to measure calf muscle HHb levels before and 3 months after UGFS. The calf venous HHb blood-filling index was calculated on standing, the calf venous HHb ejection index was obtained after one tiptoe movement, and the venous HHb retention index was obtained after 10 tiptoe movements. The primary end point was an evident improvement in calf muscle deoxygenation after UGFS. The secondary end point was obliteration of the great saphenous vein. Treatment consisted of 1% POL-F in 48 limbs and 3% POL-F in the remaining 36. Ultrasound imaging at the 3-month follow-up demonstrated complete occlusion in 56.3% of the patients who received injections of 1% POL-F and in 66.7% of those who received injections of 3% POL-F. The difference in treatment outcome between the groups was not significant (P=.333). Reflux was absent in 39 limbs (81.3%) treated with 1% POL-F and in 34 limbs (94.4%) treated with 3% POL-F, and no significant difference was observed between the two groups (P=.076). Postsclerotherapy NIRS demonstrated significant reductions in the levels of the HHb filling index in both treatment groups (P=.039, P=.0001, respectively) and significant reductions in the levels of the HHb retention index (P<.0001, P=.008, respectively). However, the differences in the levels of the HHb ejection index before and after UGFS were not significant (P=.250, P=.084, respectively). Our present findings suggest that changes in the values of these parameters may be of potential use for assessing the effects of foam sclerotherapy in patients with superficial venous insufficiency.

Activity and Energy Expenditure in Older People Playing Active Video Games

Taylor LM, Maddison R, Pfaeffli LA, Rawstorn JC, Gant N, Kerse NM. Activity and energy expenditure in older people playing active video games. ObjectivesTo quantify energy expenditure in older adults playing interactive video games while standing and seated, and secondarily to determine whether participants' balance status influenced the energy cost associated with active video game play. DesignCross-sectional study. SettingUniversity research center. ParticipantsCommunity-dwelling adults (N=19) aged 70.7±6.4 years. InterventionParticipants played 9 active video games, each for 5 minutes, in random order. Two games (boxing and bowling) were played in both seated and standing positions. Main Outcome MeasuresEnergy expenditure was assessed using indirect calorimetry while at rest and during game play. Energy expenditure was expressed in kilojoules per minute and metabolic equivalents (METs). Balance was assessed using the mini-BESTest, the Activities-specific Balance Confidence Scale, and the Timed Up and Go (TUG). ResultsMean ± SD energy expenditure was significantly greater for all game conditions compared with rest (all P≤.01) and ranged from 1.46±.41 METs to 2.97±1.16 METs. There was no significant difference in energy expenditure, activity counts, or perceived exertion between equivalent games played while standing and seated. No significant correlations were observed between energy expenditure or activity counts and balance status. ConclusionsActive video games provide light-intensity exercise in community-dwelling older people, whether played while seated or standing. People who are unable to stand may derive equivalent benefits from active video games played while seated. Further research is required to determine whether sustained use of active video games alters physical activity levels in community settings for this population.

Exercise and pregnancy: duration of labor stages and Perinea tear rates

Labor is painful, and the onset of it is full of fair for most pregnant women. In addition, women frequently suffer perinea trauma while giving birth. This study aimed to evaluate the effects of exercise on duration of labor and perinea tear rates among pregnant women. 174 women singleton gestation were selected by using a continued method, and assigned in training or a control group. They elected to follow either a light intensity exercise program throughout pregnancy until delivery. Training included 3times/week, 30–45min. Pregnancy outcomes include of duration of labor and perinea tear were recorded for two groups. Episiotomy rates, overall spontaneous tears and intact perineum rates were similar in the study and control groups (PV=0/19). The rates of intact perineum were significantly higher in the trained group (36.8% vs. 23.8%) and women in the training group had slightly lower rates of second-degree tears (40.2% vs. 53.6%), although, both of these outcomes did not reach statistical significance. There was meaningful difference between the trained and control group in duration of the first stage of labor, but it was not meaningful in duration of the second stage. The training showed neither a protective nor a detrimental significant effect on the occurrence of perinea trauma. However, exercise training during pregnancy is with a shorter labor which creates a good feeling in women.

Are Physical Performance and Injury Risk in a Professional Soccer Team in Match-Play Affected Over a Prolonged Period of Fixture Congestion?

In this study, the effects of a prolonged period of fixture congestion (8 successive official matches in 26 days) on physical performance and injury risk and severity in a professional soccer team were investigated. Computerised motion-analysis was used to analyse the overall distance covered and that run at light- (0.0-11.0 km·h - 1); low- (11.1-14.0 km·h - 1); moderate- (14.1-19.7 km·h - 1) and high-intensities (≥19.8 km·h - 1) for the team as a whole. Distances were measured in metres per minute. Information on match injuries was recorded prospectively. The overall distance covered varied across successive matches (p<0.001) as more distance was run in games 4 and 7 compared to 2 and 3, respectively (126.6 ± 12.3 m·min - 1 and 125.0 ± 13.2 m·min - 1 vs. 116.0 ± 8.0 m·min - 1 and 115.5 ± 11.0 m·min - 1). Distance run in light-intensity exercise also varied (p<0.001) as more distance was covered in game 4 vs. 1, 2, 3, 5 and 6 (75.5 ± 3.8 m·min - 1 vs. 70.6 ± 2.4 m·min - 1, 71.8 ± 3.4 m·min - 1, 69.3 ± 2.6 m·min - 1, 71.5 ± 3.1 m·min - 1, and 70.3 ± 2.8 m·min - 1) and in game 8 vs. game 3 (73.1 ± 3.8 vs. 69.3 ± 2.6 m·min - 1), respectively. When comparing match halves, there were no differences across games in overall or high-intensity distance covered and performance in these measures was similar for matches played before, during and after this period. Globally, no difference over the 8 games combined was observed between the reference team and opponents in any of the performance measures whereas the overall distance covered and that in low- (both p<0.001) and high-intensity running (p=0.040) differed in individual games. The incidence of match injury during the congested fixture period was similar to rates reported outside this period but the mean lay-off duration of injuries was substantially shorter during the former (p<0.05). In summary, while the overall distance run and that covered at lower intensities varied across games, high-intensity running performance and injury risk were generally unaffected during a prolonged period of fixture congestion. These results might be linked to squad rotation and post-match recovery strategies in place at the present club.

Improving interMediAte Risk management. MARK study

BackgroundCardiovascular risk functions fail to identify more than 50% of patients who develop cardiovascular disease. This is especially evident in the intermediate-risk patients in which clinical management becomes difficult. Our purpose is to analyze if ankle-brachial index (ABI), measures of arterial stiffness, postprandial glucose, glycosylated hemoglobin, self-measured blood pressure and presence of comorbidity are independently associated to incidence of vascular events and whether they can improve the predictive capacity of current risk equations in the intermediate-risk population.Methods/DesignThis project involves 3 groups belonging to REDIAPP (RETICS RD06/0018) from 3 Spanish regions. We will recruit a multicenter cohort of 2688 patients at intermediate risk (coronary risk between 5 and 15% or vascular death risk between 3-5% over 10 years) and no history of atherosclerotic disease, selected at random. We will record socio-demographic data, information on diet, physical activity, comorbidity and intermittent claudication. We will measure ABI, pulse wave velocity and cardio ankle vascular index at rest and after a light intensity exercise. Blood pressure and anthropometric data will be also recorded. We will also quantify lipids, glucose and glycosylated hemoglobin in a fasting blood sample and postprandial capillary glucose. Eighteen months after the recruitment, patients will be followed up to determine the incidence of vascular events (later follow-ups are planned at 5 and 10 years). We will analyze whether the new proposed risk factors contribute to improve the risk functions based on classic risk factors.DiscussionPrimary prevention of cardiovascular diseases is a priority in public health policy of developed and developing countries. The fundamental strategy consists in identifying people in a high risk situation in which preventive measures are effective and efficient. Improvement of these predictions in our country will have an immediate, clinical and welfare impact and a short term public health effect.Trial RegistrationClinical Trials.gov Identifier: NCT01428934

Deep vein thrombosis after total knee or hip arthroplasty is associated with increased preoperative calf muscle deoxygenation as measured by near-infrared spectroscopy

To assess whether the preoperative level of deoxygenated hemoglobin (HHb) in the calf muscle during light-intensity exercise is useful for identifying patients at risk of developing deep vein thrombosis (DVT) after total knee or hip arthroplasty. Sixty-eight patients undergoing total knee or total hip arthroplasty were enrolled. The Caprini risk assessment model was used to stratify patients into Caprini 5 to 6, Caprini 7 to 8, and Caprini >8 groups. The preoperative diameter of each venous segment was measured, and the time-averaged velocity (TAV) and time-averaged flow (TAF) of the popliteal vein (POPV) were assessed. Moreover, the prevalence of venous reflux in the POPV was evaluated preoperatively. Near-infrared spectroscopy (NIRS) was used to measure the calf muscle HHb level. The calf venous blood filling index (FI-HHb) was calculated on standing, and then the calf venous ejection index (EI-HHb) was obtained after one tiptoe movement and the venous retention index (RI-HHb) after 10 tiptoe movements. All patients received low-dose unfractionated heparin preoperatively and fondaparinux for postoperative thromboprophylaxis. Patients with arterial insufficiency, those who had preoperative DVT, and those who developed bilateral DVT after surgery were excluded from the study. Four patients were excluded on the basis of the exclusion criteria. Among the 64 patients evaluated, 14 (21.9%) were found to have DVT postoperatively. Among the risk factors for DVT, only the previous DVT was significantly predominant in patients who developed DVT (P = .001). The diameter of the popliteal vein was significantly smaller in patients who developed postoperative DVT than in those who did not (P = .001). Similarly, the diameter of the gastrocnemius vein was significantly larger in patients with postoperative DVT than in those without (P = .010). TAV and TAF were significantly increased in the popliteal vein in patients who developed postoperative DVT (P = .043, 0.046, respectively). Both groups showed a similar prevalence of reflux in the POPV (P = .841). The preoperative NIRS-derived RI was significantly increased in patients who developed DVT relative to those who did not (P = .004). The RI increased as the Caprini score progressed; however, there were no statistically significant differences between the three categories. Using ultrasound- and NIRS-derived parameters of significance as a unit of analysis, an optimal RI cut-off point of >2.3 showed the strongest ability to predict postoperative DVT, followed by a cut-off point >0.25 cm for the diameter of the gastrocnemius vein (GV). NIRS-derived RI >2.3 may be a promising parameter for identifying patients at risk of developing postoperative DVT despite pharmacologic DVT prophylaxis. A GV diameter of >0.25 cm also seems to contribute to the development of postoperative DVT. These results might be helpful to physicians for deciding which patients require more intensive thromboprophylaxis.

Cardiac Output Is Not Related to the Slowed O2 Uptake Kinetics in Type 2 Diabetes

This study aimed to investigate whether cardiac output (CO) responses were related to VO2 kinetics during cycling in type 2 diabetes. A total of 9 middle-aged women with uncomplicated type 2 diabetes, 9 nondiabetic overweight women, and 11 nondiabetic lean women were recruited. Initially, the ventilatory threshold (VT) and peak VO2 were determined during a maximal graded test. Then, on two separate days, subjects completed three 7-min bouts of constant-load cycling at each of three intensities: 50% VT, 80% VT, and midpoint between VT and peak VO2 (50% Δ). CO (inert gas rebreathing) was recorded at 30 and 240 s of an additional bout at each intensity. VO2 kinetic parameters were determined by fitting a biexponential (50% VT and 80% VT) or triexponential (50% Δ) function to the VO2 data. Peak VO2 was significantly lower in type 2 diabetes compared with the two nondiabetic groups (P < 0.05). The time constant of phase 2 was significantly greater (P < 0.05) in type 2 diabetes compared with the nondiabetic heavy and lean groups at 50% VT (34.2 ± 15.7 vs 15.4 ± 7.3 and 20.2 ± 9.7 s) and 80% VT (39.1 ± 9.0 vs 24.8 ± 8.8 and 36.8 ± 7.9 s), but none of the VO2 kinetic parameters were different at 50% Δ. CO responses during exercise were not different among the three groups, and at 80% VT, the change in CO from 30 to 240 s was significantly larger in type 2 diabetes compared with the two nondiabetic groups. The results confirm that type 2 diabetes slows the dynamic response of VO2 during light and moderate relative intensity exercise in females but that this occurs in the absence of any slowing of the CO response during the initial period of exercise.

Exercise Guidelines in Pregnancy

In 2002, the American College of Obstetricians and Gynecologists published exercise guidelines for pregnancy, which suggested that in the absence of medical or obstetric complications, 30 minutes or more of moderate exercise a day on most, if not all, days of the week is recommended for pregnant women. However, these guidelines did not define 'moderate intensity' or the specific amount of weekly caloric expenditure from physical activity required. Recent research has determined that increasing physical activity energy expenditure to a minimum of 16 metabolic equivalent task (MET) hours per week, or preferably 28 MET hours per week, and increasing exercise intensity to ≥60% of heart rate reserve during pregnancy, reduces the risk of gestational diabetes mellitus and perhaps hypertensive disorders of pregnancy (i.e. gestational hypertension and pre-eclampsia) compared with less vigorous exercise. To achieve the target expenditure of 28 MET hours per week, one could walk at 3.2 km per hour for 11.2 hours per week (2.5 METs, light intensity), or preferably exercise on a stationary bicycle for 4.7 hours per week (∼6-7 METs, vigorous intensity). The more vigorous the exercise, the less total time of exercise is required per week, resulting in ≥60% reduction in total exercise time compared with light intensity exercise. Light muscle strengthening performed over the second and third trimester of pregnancy has minimal effects on a newborn infant's body size and overall health. On the basis of this and other information, updated recommendations for exercise in pregnancy are suggested.

Advanced Chronic Venous Insufficiency is Associated with Increased Calf Muscle Deoxygenation

Objective To determine the temporal relationship between changes in calf muscle deoxygenated haemoglobin (HHb) measured by near-infrared spectroscopy (NIRS) during light-intensity exercise and clinical stages of chronic venous insufficiency (CVI). Design and methods Calf muscle HHb level was obtained in 168 limbs of 158 patients with various clinical stages of CVI. Clinical manifestations were categorised according to the CEAP classification (CEAP, clinical, etiological, anatomical and pathophysiological), and the patients were divided into two groups: early CVI (C 0−3,E p ,s,A s ,d,p,P r ,o) and advanced CVI (C 4−6,E p ,s, A s ,d,p,P r ,o). Calf venous blood-filling index (FI-HHb) was calculated on standing, then the calf venous ejection index (EI-HHb) was obtained after one tiptoe movement and the venous retention index (RI-HHb) after 10 tiptoe movements. Results A total of 116 limbs had early, and 52 had advanced CVI. FI and RI were significantly increased in patients with advanced CVI compared with those with early CVI ( P = 0.003, 0.0001, respectively). Similarly, RI was significantly greater in patients who had superficial, combined with deep and/or perforator, insufficiency than in patients with superficial insufficiency alone ( P = 0.002). RI showed the strongest correlation with duplex-derived peak reflux velocity in the popliteal vein ( r = 0.78, P < 0.0001). Combination of an optimal cut-off point of 0.2 for FI and 2.9 for RI improved the ability to discriminate early from advanced CVI, with a sensitivity of 94% and a specificity of 86%. Conclusions These results suggest that FI and RI, as measured by NIRS, may be promising parameters for discriminating early CVI from advanced CVI.

Yoga and Physical Activity: The Effect of Meditation

I read with a great interest the article by Buranruk and colleagues (2010) regarding measurements of cardio-respiratory parameters to assess the intensity of physical exercise in healthy adults practicing Thai Yoga. The authors conclude that a 30 minute long Thai Yoga session is commensurate to a very light to light intensity exercise. It is noteworthy that the measured physiological parameters (e.g., heart rate, VO2 max) are the function of the subtle interplay between relaxation techniques aimed at slowing down the metabolic rate by eliciting parasympathetic effect, and physical stimulation that, on the other hand, result in a strong sympathetic response. That is, it can be deduced that the levels of relaxation that one engaged in throughout the Yoga session mediates the effect of physical activity on the physiological parameters. Thus, taking into account the physiological parameters only while discarding the effect of meditation could result in miscalculation of the actual net value of the physical exercise.

Changes of exercise and the clinical effects among eldly non-small cell lung cancer survivors

背景与目的运动对健康有重要影响，可以提高癌症生存者的心血管系统功能、肌力和幸福感等，并减少乏力、焦虑、抑郁等。但目前关于肺癌患者治疗后运动能力的改变及其与肿瘤复发的关系目前尚不明了。本研究拟探讨老年非小细胞肺癌生存者体能锻炼行为模式的改变和临床意义。方法采用回顾分析方法，调查包括手术后、化放疗后病情稳定者和服用酪氨酸激酶抑制剂行靶向治疗的老年肺癌生存者，记录其诊断前、积极治疗3个月和1年的运动量和每周运动频率，了解患者运动动机和偏好，探讨运动与肿瘤复发的关系。结果调查了58例老年肺癌生存者，发现治疗期间老年肺癌生存者的体能锻炼参与比例下降，但1年后平均轻度体力活动较治疗前有增加。1年后运动基本达标的患者占75.9%（44/58），肺癌复发/进展率为20.0%（7/35），不达标的患者占24.1%（14/58），复发/进展率为35.7%（5/14），运动不达标时肿瘤复发/进展的风险比（risk ratio, RR）为2.14（95%CI:0.81-5.68, P=0.26）。肿瘤生存者运动的动机主要有改善健康、增加体能，维持正常生活方式、增加免疫力等，而最常见的障碍是疲乏、不舒服和缺少动机等。结论治疗期间老年肺癌生存者的体能锻炼参与比例降到原有的10%以下，而且即便是治疗完成后也不能恢复到诊断前的水平，运动不达标时和运动达标时患者肿瘤复发/进展的情况无明显差异，运动与肿瘤复发的关系有待进一步研究。

Thai Yoga as an Appropriate Alternative Physical Activity for Older Adults

Thai Yoga (TY), has been recommended by the Public Health Ministry of Thailand for keeping people fit. There is little known about the physiological demand it places on those practicing it. Therefore, the purpose of this study is to determine i) the exercise intensity of TY indicating by both absolute intensity (i.e. MET) and relative intensity (i.e. percentage of maximal oxygen consumption (VO2,max) and heart rate (HRmax)) and ii) the impact it has on the cardiovascular system and energy expenditure. Fourteen healthy adults ranging in age from 50 to 65 years performed 30-minute TY and exhaustive cycling exercise (to indicate maximal oxygen consumption) sessions one week apart. Mean of MET and the percentage of mean of VO2 and HR during TY to VO2,max and HRmax were found to be 1.51±0.43 METs, 35.5+/-11.9 ml/kg/min and 50.0+/-8.6 /min, respectively. The decreased HR was observed from baseline to warm up and the peak rates of energy were found to be expended in the standing posture. Results indicate that TY may be considered a very light- to light-intensity exercise. Performing longer duration in standing posture may improve cardiovascular fitness for older adults. Moreover, the relaxation component during warm up may improve psychological well-being.

The effects of exercise interventions on quality of life in clinical and healthy populations; a meta-analysis

The aim of the study was to provide an overview of the effect of exercise interventions on subjective quality of life (QoL) across adult clinical populations and well people, and to systematically investigate the impact of the exercise setting, intensity and type on these outcomes. From a systematic search of six electronic databases, 56 original studies were extracted, reporting on 7937 sick and well people. A meta-analysis was conducted on change in QoL from pre- to post-intervention compared with outcomes from a no-exercise control group, using weighted (by the study's sample size) pooled mean effect sizes and a fixed-effects model. Significant differences in outcome were found when treatment purpose was compared; prevention/promotion (well populations), rehabilitation, or disease management. Three to 6 months post-baseline, a moderate positive effect of exercise interventions was found for overall QoL in rehabilitation patients, but no significant effect for well or disease management groups. However, physical and psychological QoL domains improved significantly relative to controls in well participants. Psychological QoL was significantly poorer relative to controls in the disease management group. This pattern of results persisted over 1 year. With some exceptions, better overall QoL was reported for light intensity exercise undertaken in group settings, with greater improvement in physical QoL following moderate intensity exercise. The implications for future health care practice and research are discussed.

Development and validation of exercise target heart rate zones for overweight and obese pregnant women

Validated target heart rate (THR) zones for exercise prescription for overweight and obese pregnant women have not been developed. The purposes of this study were to determine if heart rate reserve (HRreserve) is best described by aerobic capacity at peak exercise or by aerobic capacity reserve (VO2 reserve) and to develop and validate THR zones for light-intensity exercise (20%-39%VO2 reserve) in sedentary overweight and obese pregnant women. One hundred six women between 16 and 20 weeks gestation with medical clearance performed a progressive treadmill test to volitional fatigue (peak). Data from every 4th subject were used for cross-validation. Two linear regression equations were performed for each subject, then pooled to obtain mean group values (+/- SD): %HRreserve vs. %VO2 peak and %HRreserve vs. %VO2 reserve. THR zones equivalent to 20%-39%VO2 reserve were developed and validated based on the strongest relationship. %HRreserve had a stronger linear relationship with %VO2 reserve (y = 1.046x -7.561; R2 = 0.741) than %VO2 peak (y = 1.259x -28.795; R2 = 0.604). Validated THR ranges for sedentary overweight and obese pregnant women are 102-124 beats.min-1 (20-29 years of age) and 101-120 beats.min-1 (30-39 years of age), representing an exercise intensity of 20%-39%VO2 reserve as recommended by the American College of Sports Medicine for previously sedentary pregnant women. Overweight and obese women who are medically prescreened can exercise during pregnancy within our validated THR zones. The relationship between HR and VO2 remains strong, but the two are not equivalent in this population group.

An extension to the compartmental model of type 1 diabetic patients to reproduce exercise periods with glycogen depletion and replenishment

The purpose of this work is to present the main interactions promoted by exercise and synthesize them into mathematical equations. It is intended to extend the ability of the compartmental glucose–insulin model introduced by Sorensen [1985. A physiologic model of glucose metabolism in man and its use to design and assess improved insulin therapies for diabetes. Ph.D. Dissertation, Chemical Engineering Department, MIT, Cambridge] to reproduce variations in the blood glucose concentration induced by exercise in diabetic patients and to complement the previous work by Lenart and Parker [2002. Modeling exercise effects in type I diabetic patients. In: Proceedings of the 15th Triennial World Congress, Barcelona, Spain] and Lenart, DiMascio and Parker [2002. Modeling glycogen–exercise interactions in type I diabetic patients. In: Proceedings of the A.I.Ch.E. Annual Meeting, Indianapolis, IN]. The immediate consequences of exercise are incorporated in this research: redistribution of blood flows, increments in peripheral glucose and insulin uptakes, and increment in hepatic glucose production. The extended model was verified with experimental data for light and moderate intensity exercise. In addition, data extrapolation was introduced to simulate heavy intensity exercise. The hepatic glycogen reservoir limits the peripheral glucose uptake for prolonged exercise. Therefore, the depletion and replenishment of hepatic glycogen were modeled, looking to reproduce the blood glucose levels for a type 1 diabetic patient during a normal day, with meal intakes, insulin infusions and/or boluses, and a predefined exercise regime. From the extensive simulation evaluation, it is found that the new exercise model provides a good approximation to the available experimental data from literature.