Submaximal Step Test Research Articles

Steps That Count: The Association Between the Number and Intensity of Steps Accumulated and Fitness and Health Measures

Pedometer-based recommendations for accumulating steps/d largely focus on volume, with less emphasis on intensity and fitness/health outcomes. We aim to examine this relationship. A convenience sample (N = 70, 35 men, 32 ± 8yrs) wore a pedometer (4 days). The pedometer classified steps as "aerobic" (≥ 60 steps/minute, minimum duration of 1 minute) or "non-aerobic" (< 60 steps/minute and/or < 1 minute). Estimated maximal oxygen uptake (VO2max), derived from a 12-minute submaximal step-test, and health outcomes: blood pressure (BP), body mass index (BMI), percentage body fat (%BF), and waist circumference (WC) were correlated with pedometer data. Participants were grouped according to number and intensity of steps: LOW (< 5000 steps/d), HIGH-LOW (≥ 5000 steps/d, no aerobic steps), HIGH-HIGH (≥ 5000 steps/d, including some aerobic steps). Analyses of covariance, adjusting for age, gender, and total steps/d were used to compare groups. Average steps/d was 6520 ± 2306. Total steps/d and total time spent accumulating "aerobic" steps (minutes/day) were inversely associated with %BF, BMI, WC, and systolic BP (P < .05). After adjusting for gender and total steps/d, %BF was different between all 3 groups, VO2max was different between the LOW and HIGH-HIGH groups, WC was lower in the HIGH-HIGH versus the other 2 groups (P < .03, respectively). Intensity seems an important factor to consider in steps/d cut-points.

Cardiorespiratory fitness and physical activity in Luo, Kamba, and Maasai of rural Kenya

BackgroundAlthough habitual physical activity energy expenditure (PAEE) and cardio-respiratory fitness (CRF) are now well-established determinants of metabolic disease, there is scarcity of such data from Africa. The aim of this study was to describe objectively measured PAEE and CRF in different ethnic populations of rural Kenya.MethodsA cross-sectional study was done among 1,099 rural Luo, Kamba, and Maasai of Kenya. Participants were 17–68 years old and 60.9% were women. Individual heart rate (HR) response to a submaximal steptest was used to assess CRF (estimated VO2max). Habitual PAEE was measured with combined accelerometry and HR monitoring, with individual calibration of HR using information from the step test.ResultsMen had higher PAEE than women (∼78 vs. ∼67 kJ day−1 kg−1, respectively). CRF was similar in all three populations (∼38 and ∼43 mlO2·kg−1 min−1 in women and men, respectively), while habitual PAEE measures were generally highest in the Maasai and Kamba. About 59% of time was spent sedentary (<1.5 METs), with Maasai women spending significantly less (55%). Both CRF and PAEE were lower in older compared to younger rural Kenyans, a difference which was most pronounced for PAEE in Maasai (−6.0 and −11.9 kJ day−1 kg−1 per 10-year age difference in women and men, respectively) and for CRF in Maasai men (−4.4 mlO2·min−1 kg−1 per 10 years). Adjustment for hemoglobin did not materially change these associations.ConclusionPhysical activity levels among rural Kenyan adults are high, with highest levels observed in the Maasai and Kamba. The Kamba may be most resilient to age-related declines in physical activity. Am. J. Hum. Biol. 2012. © 2012 Wiley Periodicals, Inc.

Trends in aerobic fitness among Canadians, 1981 to 2007–2009

Public health surveillance systems often monitor physical activity trends, but fitness assessment is relatively rare. This study investigated secular changes in aerobic fitness among Canadian adults and children. Participants aged 8-69 years were from 2 nationally representative surveys, conducted in-home in 1981 and in mobile examination centers in 2007-2009. In both surveys, submaximal step tests using progressive age- and sex-specific exercise stages were completed after initial screening (Physical Activity Readiness Questionnaire, heart rate, blood pressure). Between surveys, the step-test protocol had been modified to reduce underestimation of fitness among fitter and older individuals. Maximal oxygen uptake was estimated for adults using validated historical and updated prediction equations, adjusted to reflect protocol differences. Because these equations are not validated for young people, maximal aerobic power was predicted at a heart rate of 200 beats·min(-1) by regressing observed heart rates on the oxygen costs of stepping for children and youth who completed at least 2 exercise stages. Overall, despite protocol differences, we found that the aerobic fitness levels of Canadians were lower in 2007-2009 than in 1981, with declines apparent in all age and both sex groups, thereby increasing the number of those at risk of adverse health outcomes. Future work is required to validate prediction equations of aerobic fitness for young people to make it possible to compare fitness levels over the lifespan and across time.

Perfil fisiológico de uma aula de body step

O objetivo do estudo foi determinar o perfil fisiologico da aula de Body Step® (BS) por meio da frequencia cardiaca (FC) e concentracao de lactato sanguineo ([La]). Onze mulheres (25 ± 4 anos; 59,5 ± 5,5 kg; 164,2 ± 7,5 cm; 22,8 ± 2,6% de gordura corporal) praticantes da modalidade foram submetidas a duas intervencoes: um teste submaximo de banco e uma aula de BS. A FCpico e a FCmedia encontradas durante a aula foram 182 ± 9 e 142 ± 12 bpm, respectivamente. O gasto calorico total estimado da aula foi de 480,7 ± 79,3 kcal. Em relacao a [La], as participantes do estudo permaneceram em 58,3% das musicas dentro do dominio pesado, 25% no dominio moderado e 16,7% no severo. Pode-se concluir que a aula de BS apresentou elevada intensidade confirmada a partir dos indicadores fisiologicos mensurados, os quais estao adequados para o aprimoramento da capacidade aerobia.

Physical activity, cardio‐respiratory fitness, and metabolic traits in rural mexican tarahumara

ObjectivesTo study the association between physical activity energy expenditure (PAEE) and cardio-respiratory fitness (CRF) with key metabolic traits and anthropometric measures in the Tarahumara of Mexico.MethodsA cross-sectional study was carried out in five rural communities in Chihuahua, México including 64 adult Tarahumara, mean (SD) age 40.7 (12.9) years. Using a combined accelerometer and heart rate sensor, PAEE was measured over three consecutive days and nights and a sub-maximal step test was carried out in order to (1) calibrate heart rate at the individual level and (2) to estimate CRF. Random blood glucose level and resting blood pressure (BP) were measured with standard anthropometrics.ResultsMean (SD) PAEE was 71.2 (30.3) kJ kg−1 day−1 and CRF was 36.6 (6.5) mlO2 min−1 kg−1. Mean (SD) glucose was 127.9 (32.4) mg/dl, with 3.3% having diabetes. Mean (SD) systolic and diastolic BP was 122 (20.8) and 82 (14.8) mm Hg, respectively, with 28.1% having hypertension. Mean body mass index was 27.5 (4.2) kg m−2, with 71.9% being overweight. Following adjustment for age and sex, weak inverse associations were observed between PAEE and systolic BP (β = −0.20, P = 0.27) and diastolic BP (β = −0.16, P = 0.23); and between CRF and systolic BP (β = −0.51, P = 0.14) and diastolic BP (β = −0.53, P = 0.06). The inverse associations with glucose were also weak and not statistically significant for neither PAEE (β = −0.01, P = 0.63) nor CRF (β = −0.05, P = 0.27).ConclusionsThis study suggests high levels of overweight and hypertension in the Tarahumara, and points to fitness and physical activity as potential intervention targets although findings should be confirmed in larger samples. Am. J. Hum. Biol. 2012. © 2012 Wiley Periodicals, Inc.

The Impact of a 3-Year After-School Obesity Prevention Program in Elementary School Children

Children tend to be sedentary during the after-school hours, and this has deleterious effects on their health. The objective of the present study was to determine the effects of a 3-year after-school physical activity (PA) program, without restriction of dietary energy intake, on percent body fat (%BF), cardiorespiratory fitness (CRF), and cardiometabolic markers in children. A cluster randomization design was employed. A total of 574 3rd grade children from 18 elementary schools in the southeastern United States participated. The intervention consisted of 80 minutes of age-appropriate moderate-to-vigorous PA each school day. The main outcomes of interest were %BF measured by dual-energy X-ray absorptiometry; CRF measured by heart rate in response to a submaximal step test; nonfasting total and high-density lipoprotein cholesterol (HDL-C); and resting blood pressure (BP). Intent-to-treat analyses showed significant treatment by time interactions for %BF (p = 0.009) and CRF (p = 0.0003). The change pattern of the means suggested that %BF and CRF in intervention children improved relative to control children during the school months, rebounding to the levels of control children over the summers following years 1 and 2. Year-by-year analyses of what occurred during the months when the program was offered revealed dose–response relations for %BF and CRF, such that the clearest beneficial effects were seen for those youth who attended at least 60% of the after-school sessions. No significant intervention effects were seen for cholesterol or BP. An after-school PA program was effective in reducing adiposity and improving CRF, especially in the children who attended the sessions at least 3 days/week. However, the favorable effects on %BF and CRF were lost over the summer. Thus, it is critical to incorporate strategies that attract and retain the children to receive an adequate dose of PA year-round.

Lower cardiorespiratory fitness in children with Type 1 diabetes

The present study aimed to compare cardiorespiratory fitness levels in children with and without Type 1 diabetes. In addition, the relationship between cardiorespiratory fitness and a range of physical and clinical factors was investigated. Eighty-eight children with Type 1 diabetes aged 5-14 years completed a submaximal step test of cardiorespiratory fitness. Sixty-two of these children were successfully matched to control subjects without diabetes based on age, sex and anthropometrics for comparison. In addition, the relationship between cardiorespiratory fitness and a range of physical and clinical variables was assessed in the children with diabetes. The heart rate response to exercise was higher in children with Type 1 diabetes, indicating reduced cardiorespiratory fitness levels compared with control subjects. Both gender and glycaemic control (HbA(1c) ) were significantly associated with cardiorespiratory fitness, with female sex and poorer glycaemic control associated with reduced fitness. Future research should investigate whether the reduced fitness in children with Type 1 diabetes is attributable to lower physical activity levels, or physiological changes resulting from the diabetes pathology itself.

Objectively assessed physical activity, fitness and subjective wellbeing

Background The existing evidence for a cross-sectional association between physical activity and subjective wellbeing is inconsistent, mainly because of the reliance on self reported physical activity, which might have conceptual overlap with subjective health. Purpose To examine associations of objectively assessed physical activity and cardiorespiratory fitness with subjective wellbeing. Methods A sub-sample of participants (921 men and women, mean age 44.6 ± 15.0 yrs, 46.4% men) from the 2008 Health Survey for England completed objective measures of physical activity (Actigraph) and an 8 min sub-maximal step test to estimate levels of cardiorespiratory fitness. The General Health Questionnaire and self-rated health was used as indicators of subjective wellbeing. Results The recorded levels of moderate to vigorous physical activity (MVPA) were higher in participants reporting very good health (adjusted mean difference = 6.7, 95% CI, 1.1–12.4 min/d, p = 0.019) compared with participants reporting fair–poor health after adjustment for various confounders and fitness level. Neither physical fitness, objectively assessed sedentary time or light activity was related to self-rated health. There was also no association between objectively measured physical activity and fitness with psychological health, despite a robust association with self reported MVPA in the overall sample. Conclusions Objectively assessed MVPA is independently associated with self-rated health. Self reported, but not objectively assessed MVPA, was associated with psychological health. The null findings with regards to psychological health might partly reflect selection biases associated with the healthy nature of this sub-sample of participants.

Evaluation of three methodologies to estimate the VO 2max in people of different ages

Aging and gender are factors that affect the variation of physical work capacity. The present paper highlights the importance of the metabolism used by ergonomics to establish the appropriate limits of loads at work. This study compares the aerobic capacity of people from 20 to 71 years old split in 5 different groups. The laboratory experiment tested 33 volunteers (19 women and 14 men). A submaximal step test was used to measure the VO 2 using a portable breath by breath metabolic system and a telemetric heart rate monitor. Three methods to estimate the VO 2max were compared: 1) a direct measurement of VO 2, 2) estimation by heart rate, and 3) a step test method using predetermined charts. Significant difference was encountered among the estimation methods as well as among the age ranges ( F 2,92 = 6.43, p < 0.05 y F 4,92 = 7.18, p < 0.05 respectively). The method of direct measurement and the method of predetermined charts were different for the estimation of the VO 2max with a confidence level of 95%. The method of predetermined charts is better adapted for males and people younger than 30 years. The estimation through non invasive heart rate apparatus was a good appraiser of the maximal oxygen consumption considering both genders and all the age groups.

Micro- And Macro-level Correlates Of Adiposity In Children

PURPOSE: To examine race and sex differences in adiposity measured by dual-energy x-ray absorptiometry in a large sample of young children and to identify both micro-level and macro-level correlates of adiposity. METHODS: Participants were elementary school children (N=495) from the southeastern United States. Measurements were anthropometrics, body fat via dual-energy x-ray absorptiometry, cardiovascular fitness via sub-maximal step test, psychosocial variables via questionnaire, community level sociodemographic data and built environment variables via GIS. RESULTS: Percent body fat in white children was higher than in non-white children. Higher percent body fat and poorer cardiovascular fitness was found in females compared to males. The full mixed model indicated that higher percent body fat was significantly associated with being female, lower cardiovascular fitness, lower Athletic Competence, and higher percent of minority population in the neighborhood. CONCLUSIONS: This study provides limited support for a social ecological perspective in explanation of variations in adiposity in children. Findings suggest that children's sociodemographic environment is an important factor to consider when designing obesity prevention programs for children and that development of athletic competence should be a goal of physical activity promotion programs.

Hierarchy of individual calibration levels for heart rate and accelerometry to measure physical activity

Combining accelerometry with heart rate (HR) monitoring may improve precision of physical activity measurement. Considerable variation exists in the relationships between physical activity intensity (PAI) and HR and accelerometry, which may be reduced by individual calibration. However, individual calibration limits feasibility of these techniques in population studies, and less burdensome, yet valid, methods of calibration are required. We aimed to evaluate the precision of different individual calibration procedures against a reference calibration procedure: a ramped treadmill walking-running test with continuous measurement of PAI by indirect calorimetry in 26 women and 25 men [mean (SD): 35 (9) yr, 1.69 (0.10) m, 70 (14) kg]. Acceleration (along the longitudinal axis of the trunk) and HR were measured simultaneously. Alternative calibration procedures included treadmill testing without calorimetry, submaximal step and walk tests with and without calorimetry, and nonexercise calibration using sleeping HR and gender. Reference accelerometry and HR models explained >95% of the between-individual variance in PAI (P < 0.001). This fraction dropped to 73 and 81%, respectively, for accelerometry and HR models calibrated with treadmill tests without calorimetry. Step-test calibration captured 62-64% (accelerometry) and 68% (HR) of the variance between individuals. Corresponding values were 63-76% and 59-61% for walk-test calibration. There was only little benefit of including calorimetry during step and walk calibration for HR models. Nonexercise calibration procedures explained 54% (accelerometry) and 30% (HR) of the between-individual variance. In conclusion, a substantial proportion of the between-individual variance in relationships between PAI, accelerometry, and HR is captured with simple calibration procedures, feasible for use in epidemiological studies.

Improved Type 2 Diabetes Patient Outcomes and Projected Cost Savings Following Supervised Exercise Training

Physical activity has long been a primary intervention to manage type 2 diabetes. PURPOSE: Because type 2 diabetes outpatients do not always follow the recommendation by health care professionals to exercise, this project followed 8 outpatients referred to the Diabetes Education Centre (DEC) by their primary care physician who agreed to participate in a kinesiologist-directed exercise training program offered at the Hospital for 11 months. METHODS: 2 males and 6 females (60.9 ± 10.4 years; 93.7 ± 25.9 kg; 162.3 ± 10.1 cm; means ± SD) completed testing before, after 3 months and after 11 months of training. They exercised in a supervised setting (combination of up to 25 minutes of aerobic, up to 25 minutes of resistance and 10 minutes of flexibility exercises) twice a week for ∼11 months. RESULTS: Compared to baseline measures, early (i.e. 3 months) significant findings included improvements in aerobic capacity assessed using a submaximal step test (114%), grip strength (14%), push-ups (670%), curl-ups (234%), as well as functional capacity assessed using the sit-to-stand tests (56, 15 and 14%). Long term effects (i.e. 11 months) also included significant decreases in systolic blood pressure from 131 to 122 mmHg and decreases in sum of 2 and sum of 5 skin folds by 16 and 12% respectively. There were no significant changes in blood work including lipid profile however hemoglobin A1C exhibited a clinically relevant decrease from 7.1 % to 6.1 % after 11 months of intervention in this group. Collectively, these improvements in patient outcomes have been associated with improvements in quality of life and cost savings. Based on the observed changes in hemoglobin A1C and blood pressure alone and using the data of Palmer et al. (Current Medical Research and Opinion, 2004; 20, S53-S58.), we can conservatively project a lifetime cost savings of ∼$11000 US per patient. The cost of providing the kinesiologist-directed exercise training will offset part of these savings; however, indirect costs of physical inactivity would also be reduced by a program of this type. Future research should identify the long-term adherence parameters required to maintain the observed patient outcomes and further delineate the cost-savings analysis. CONCLUSION: The results of this project suggest the addition of a kinesiologist to the multidisciplinary health care team in a DEC will have significant long term health benefits for type 2 diabetes outpatients and can contribute to reducing health care costs in this population. Supported by the Nova Scotia Health Research Foundation, Eastern Kings Memorial Health Foundation and Thera-Band ®.

Relationships of Heart Rate and Movement with Physical Activity Intensity

Combining accelerometry (ACC) with heart rate (HR) monitoring may improve the precision of physical activity intensity (PAI) measurement, compared with either method used alone. Considerable between-individual variation exists in ACC/HR-PAI relationships, which may be reduced by individual calibration. However, most existing methods are not suitable for use in large populations. PURPOSE: To evaluate the precision of different procedures for individual calibration against a criterion calibration procedure. METHODS: A total of 75 participants [mean (SD): 32.7 (8.4) yrs; 1.71 (0.11) m; 70.3 (14) kg] performed a ramped treadmill walking-running test with continuous measurement of PAI by indirect calorimetry (criterion calibration procedure). ACC along the longitudinal axis of the trunk and HR were measured simultaneously. Alternative calibration procedures included treadmill testing without direct measurement of PAI, a sub-maximal step test with and without direct PAI measurement, and non-exercise calibration using sleeping HR, resting HR variability, hemoglobin concentration, and sitting stroke volume obtained by inert gas re-breathing. RESULTS: Standard errors of the estimates (SEE) for the criterion ACC and HR models were 78 (R2=.87) and 35 J min−1 kg−1 (R2=.97), respectively. Errors increased 10 and 40%, respectively, for the calibration procedure using a treadmill test without measuring PAI. Step test calibration procedures explained 83 (for ACC) and 90% (for HR) of the variance (SEE>68 J min−1 kg−1), irrespective of whether PAI measurement during the step test was included. Non-exercise calibration procedures explained ∼80% of the variance in PAI (SEE<93 J min−1 kg−1). By contrast to hemoglobin, including a measure of sitting stroke volume increased the explained variance in PAI, especially in the model utilizing the step test without direct PAI measurement. Combining ACC with HR improved measurement precision at the extremes of the PAI spectrum. CONCLUSIONS: A high degree of the between-individual variance in the ACC/HR-PAI relationships can be accounted for with simple calibration procedures, feasible for use in large epidemiological studies.

The Chester step test—a simple yet effective tool for the prediction of aerobic capacity

Objectives The assessment of cardiorespiratory fitness is becoming more commonplace in both community and occupational health settings. This study investigates the reliability and validity of the Chester step test, a submaximal test for the prediction of aerobic capacity, when compared to maximal oxygen uptake (V̇O 2Max) measured during a treadmill test. Design Participants completed a V̇O 2Max Treadmill Test using a standardised fast incremental ramp protocol designed to elicit exhaustion in 8–12 minutes. Following this, on separate days, subjects then completed the Chester step test (CST) on two occasions (CST1 and CST2). During the submaximal step test, subjects were asked to step on to and off a 30-cm step at a rate set by the metronome beat on an audio cassette. The initial step rate was 15 steps per minute and every 2 minutes the tempo increased by 5 steps per minute. The subject continued stepping until he/she reached 80% of their maximum predicted heart rate, or reported a rating of perceived exertion of 15 (hard) on the Borg scale, or reached the end of the 10-minutes 5-stage test. Setting Human Performance Laboratory, University College Chester Participants Sixty-eight subjects (mean age 30.6±9.7 years; range 18–52 years) with a wide range of ages and abilities Main outcome measures Gas exchange and heart rate were measured continuously using a Polar heart rate monitor. Heart rate and rating of perceived exertion were recorded after each 2-minute stage. Results Results revealed a high correlation ( r=0.92) between V̇O 2Max and CST1 ( P<0.001) and a standard error of the estimate of 3.9 ml O 2/kg/min, thus confirming the face validity of CST as a predictor of V̇O 2Max. Using the method of analysis recommended by Bland and Altman (1986) [Lancet 5 (1986) 307] the mean difference between repeated predicted measures using CST was −0.7 ml O 2/kg/min. The limits of agreement analysis also demonstrated that a measurement repeated on a separate day was within 4.5 ml O 2/kg/min of the original predicted measurement. The Chester step test is therefore appropriate for use in situations where a change in aerobic capacity is expected to be more than 3.8 ml O 2/kg/min higher or more than 5.2 ml O 2/kg/min lower than the baseline measurement. Conclusions The Chester step test was shown to be a valid test for the estimation of aerobic capacity within this group. The error of measurement is sufficiently small and suggests that this method is well suited to monitoring changes in aerobic capacity in rehabilitation settings.

Physical activity, physical fitness, and insulin and glucose concentrations in an isolated Native Canadian population experiencing rapid lifestyle change.

Little is known about the relation of physical activity and physical fitness to insulin resistance and glucose intolerance in isolated subarctic Native Canadian populations. The purpose of this effort was to examine the relation between activity and fitness and obesity and glucose concentrations in such a unique population. This study describes 530 men and women from the community of Sandy Lake, Ontario, located in the boreal forest region of central Canada. Fasting blood glucose and insulin concentrations were determined after an overnight fast. Past year physical activity levels were assessed using a modified version of an interviewer-administered questionnaire. Maximal oxygen uptake, a measure of cardiovascular fitness, was estimated using a submaximal step test. Total (leisure and occupational) physical activity and physical fitness were significantly associated with fasting insulin concentrations after adjusting for age, BMI or percent body fat, waist circumference, and fasting glucose concentration in men but not in women. The relations between physical activity, fitness, and fasting glucose concentrations were not as strong or as consistent as they were when fasting insulin concentration was the dependent variable. In this isolated Native Canadian community, both physical activity and fitness were independently associated with fasting insulin concentrations, suggesting a beneficial role of physical activity/fitness on insulin sensitivity that is separate from any influence of activity on body composition. The fact that this relation was found in men but not in women is most likely explained by issues related to the measurement of activity and fitness in this study and the fact that the women in this population appear to be less active than the men.

The influence of supporting the Oxylog instrument on estimated maximal aerobic capacity during a step test and heart rate in a lifting test

This study investigated the influence of wearing, an Oxylog mask and heart rate monitor while the Oxylog instrument was supported in a stand versus that of wearing the Oxylog mask, heart rate monitor, and the Oxylog instrument, on oxygen consumption ( V ̇ O 2) and heart rate response during a graduated submaximal step test protocol. Also, the predicted maximal aerobic capacities ( V ̇ O 2max) produced by the two graduated step tests were compared. In addition, differences in the working heart rates in a submaximal lifting test were analyzed in two lifting tests, one with the participant wearing the Oxylog mask, heart rate monitor, and Oxylog instrument and the other required the participant to only wear a heart monitor. Seventeen experienced male manual materials handlers participated in the study, and each treatment was seen by each participant in a randomized Latin Square design. Results from the two investigations indicate that there was no significant difference in the estimated maximal oxygen consumption ( p=0.1384) and no significant difference in the heart rate between the two lift tests. The analysis did show that the 4th stage (participants reaching their physiological limits) of the step tests indicated a statistically significant difference ( p=0.0259 for oxygen consumption, and p=0.0465 for heart rate).

An evaluation of physiological demands and comfort between the use of conventional and lightweight self-contained breathing apparatus

The additional physiological strain associated with the use of self-contained breathing apparatus (SCBA) is mostly linked to the additional weight. Lightweight and conventional SCBA were assessed in a submaximal step test performed in full firekit (total weights 15 and 27 kg, respectively). Factors assessed were: comparative energy expenditure of the two sets, relationship between comparative energy expenditure and aerobic fitness and subjective discomfort. Measured variables were: oxygen consumption, heart rate, estimated VO 2max and subjective discomfort (body part discomfort scale). The lightweight SCBA displayed a significant oxygen consumption benefit, which was independent of dynamic workrate and valued at 0.256 l min −1. Mean heart rate responses were significantly lower with the light set. No relationship was found between comparative energy expenditure and aerobic fitness. The light set was rated as significantly more comfortable than the heavy. Further research is required to assess the extent of the energy consumption benefit in realistic fire suppression protocols and the contribution of ergonomic factors to the energy and comfort benefits.

A modified step test based on a function of subjects' stature.

A number of submaximal step tests have been developed to predict maximal aerobic capacity. Because step height may influence biomechanical efficiency and heart rate, step tests based on subjects' stature may more accurately predict maximal aerobic capacity. Eighteen women performed the Queens College step test and a modified Queens College step test. The modified step test was performed with the height of the bench set even with the height of the foot at a knee angle of 90 degrees. Analysis of the data indicated a lower recovery heart rate following this test (p < .05). Further, correlations between maximal aerobic capacity and recovery heart rate for both tests were moderate (r = -.80 and -.75, respectively). Our results suggest that step tests based on subjects' stature do not more accurately predict aerobic capacity than those using a standardized bench height.

Screening Adolescent Athletes for Exercise-Induced Asthma

To pilot test an exercise-induced asthma (EIA) screening program using a submaximal step-test and pulmonary function test (PFT) to identify athletes with EIA and to determine if a physical examination or self-reported history could be used to predict the existence of EIA. Screening and diagnostic testing using a convenience sample. Birmingham, Alabama, during athletic preparticipation examination (PPE). Fifty-two African-American, male football players aged 14-18 years being evaluated for participation in scholastic athletics. No athlete refused participation. Four were excluded because of need for further evaluation unrelated to any pulmonary condition. Each athlete completed a medical history, allergy history, physical examination, preexercise pulmonary function test (PFT), submaximal step-test, and a series of postexercise PFTs. Major outcome measurements were changes in forced expiration volume in 1s (FEV1) or peak expiratory flow rate (PEFR) after completing an exercise challenge. Seventeen of 48 athletes had a > or = 15% decrease in PEFR after exercise. Nine of 48 athletes had a > or = 15% decrease in FEV1 after exercise. The only self-reported item that differentiated subjects with normal and abnormal PFTs was a personal history of asthma (p < 0.05). Many athletes can be identified as having abnormal PFTs by use of a submaximal step-test as an exercise challenge. Self-reporting questionnaires and PPEs do not appear to be sensitive enough to identify athletes with this condition. If validated by future studies, this protocol could be used for the diagnosis of EIA.

Prediction of Maximal Oxygen Uptake From a Modified Canadian Aerobic Fitness Test

The purpose of the present study was to increase the accuracy of prediction of VO2max from the Canadian Aerobic Fitness Test (CAFT) by modifying the protocol and developing a new equation. Males and females between the ages of 15 and 69 years (n = 129) were tested on four occasions. Each subject performed four submaximal step tests (modified CAFT protocol) and a maximal treadmill test. The modification of the protocol consisted of allowing each subject to complete the number of stages needed to reach a target heart rate of 85% of age-predicted maximum. This required adding a new Stage 8 for men and Stages 7 and 8 for women. The prediction equation resulting from regression analysis was, VO2max (ml.kg-1 x min-1) = 32.0 + 16.0 VO2 - 0.24 Age - 0.17 Wt (R2 - 0.77; delta 2 - 26.6), where VO2 = oxygen cost of stepping at the final level (L.min-1), Age = age (yrs), and Wt = body mass (kg).