Training effects of cross-country skiing and running on maximal aerobic cycle performance and on blood lipids

Summary Two experiments were carried out to compare the cardiorespiratory and metabolic effects of cross-country skiing and running training during two successive winters. Forty-year-old men were randomly assigned into skiing (n = 15 in study 1,n = 16 in study 2), running (n = 16 in study 1 andn = 16 in study 2) and control (n = 17 in study 1 andn = 16 in study 2) groups. Three subjects dropped out of the programme. The training lasted 9–10 weeks with 40-min exercise sessions three times each week. The training intensity was controlled at 75%–85% of the maximal oxygen consumption (VO_2max) using portable heart rate metres and the mean heart rate was 156–157 beats·min^–1 in the training groups. In the pooled data of the two studies the mean increase in theVO_2max (in ml·min^–1·kg^–1) on a cycle ergometer was 17% for the skiing group, 13% for the running group and 2% for the control group. The increase inVO_2max was highly significant in the combined exercise group compared to the control group but did not differ significantly between the skiing and running groups. The fasting serum concentrations of lipoproteins and insulin did not change significantly in any of the groups. These results suggested that training by cross-country skiing and running of the same duration and intensity at each session for 9–10 weeks improved equally the cardiorespiratory fitness of untrained middle-aged men.     

Influence of acute maximal exercise on lecithin: cholesterol acyltransferase activity in healthy adults of differing aerobic performance

Summary To document the possible influence of a single episode of maximal aerobic stress on the serum lecithin: cholesterol acyltransferase (LCAT) activity in subjects with differing histories of training, two groups of healthy male adults [controls (C),n = 18, 28.6 years, SD 5.2, 50.1 ml · kg^–1 · min^–1 maximal O₂ uptake (VO_2max), SD 5.3; endurance trained athletes (T),n = 18, 31.4 years, SD 8.8, 65.0 ml · kg^–1 · min^–1 VO_2max, SD 2.8] were examined in a maximal aerobic stress test. In addition to the routine assessment of lipid status, LCAT activity was measured immediately before and after exercise. At rest nearly identical LCAT activity values were found in both groups: C 64.4 nmol · ml^–1 · h^–1, SD 16.7 vs T 65.0 nmol · ml^–1 · h^–1, SD 20.9. The post-exercise LCAT values induced by the maximal stress test increased significantly to (C) 95.7 nmol · ml^–1 · h^–1, SD 23.5, +48.6%,P<0.001; (T) 83.5 nmol · ml^–1 · h^–1, SD 24.3, +29.1%,P<0.01. Neither the pre nor the post-exercise individual LCAT activity values showed any significant correlation to the corresponding data on physical performance.     

Maximal oxygen uptake,anaerobic threshold and running economy in women and men with similar performances level in marathons

Sex differences in running economy (gross oxygen cost of running, C_R), maximal oxygen uptake (VO_2max), anaerobic threshold (Th_an), percentage utilization of aerobic power (% VO_2max), and Th_an during running were investigated. There were six men and six women aged 20–30 years with a performance time of 2 h 40 min over the marathon distance. The VO_2max, Th_an, and CR were measured during controlled running on a treadmill at 1° and 3° gradient. From each subject's recorded time of running in the marathon, the average speed (v _M) was calculated and maintained during the treadmill running for 11 min. The VO_{2 max} was inversely related to body mass (m _b), there were no sex differences, and the mean values of the reduced exponent were 0.65 for women and 0.81 for men. These results indicate that for running the unit ml·kg^–0.75·min^–1 is convenient when comparing individuals with different m _b. The VO_2max was about 10% (23 ml·kg^–0.75·min^–1) higher in the men than in the women. The women had on the average 10–12 ml·kg^–0.75·min^–1 lower VO₂ than the men when running at comparable velocities. Disregarding sex, the mean value of C_R was 0.211 (SEM 0.005) ml·kg^–1·m^–1 (resting included), and was independent of treadmill speed. No sex differences in Th_an expressed as % VO_2max or percentage maximal heart rate were found, but Than expressed as VO₂ in ml·kg^–0.75·min^–1 was significantly higher in the men compared to the women. The percentage utilization of f _emax and concentration of blood lactate at v _M was higher for the female runners. The women ran 2 days more each week than the men over the first 4 months during the half year preceding the marathon race. It was concluded that the higher VO_2max and Th_an in the men was compensated for by more running, superior C_R, and a higher exercise intensity during the race in the performance-matched female marathon runners.     

Sex differences in performance-matched marathon runners

Summary Six male and six female runners were chosen on the basis of age (20–30 years) and their performance over the marathon distance (mean time = 199.4, SEM 2.3 min for men and 201.8, SEM 1.8 min for women). The purpose was to find possible sex differences in maximal aerobic power (VO_2max), anaerobic threshold, running economy, degree and utilization of VO_2max (when running a marathon) and amount of training. The results showed that performance-matched male and female marathon runners had approximately the same VO_2max (about 60 ml·kg^–1·min^–1). For both sexes the anaerobic threshold was reached at an exercise intensity of about 83% of VO_2max, or 88%–90% of maximal heart rate. The females' running economy was poorer, i.e. their oxygen uptake during running at a standard submaximal speed was higher (P<0.05). The heart rate, respiratory exchange ratio and blood lactate concentration also confirmed that a given running speed resulted in higher physiological. strain for the females. The percentage utilization of VO_2max at the average marathon running speed was somewhat higher for the females, but the difference was not significant. For both sexes the oxygen uptake at average speed was 93%–94% of the oxygen uptake corresponding to the anaerobic threshold. Answers to a questionnaire showed that the females' training programme over the last 2 months prior to running the actual marathon comprised almost twice as many kilometres of running per week compared to the males (60 and 33 km, respectively). The better state of training of the females was also confirmed by a 10% higher VO_2max, in relation to lean body mass than that of the male runners. Apart from the well-known variation in height and differences in the percentage of fat, the difference between performance-matched male and female marathon runners seemed primarily to be found in running economy and amount of training.     

Caffeine increases maximal anaerobic power and blood lactate concentration

Summary The aim of this study was to specify the effects of caffeine on maximal anaerobic power (W _max). A group of 14 subjects ingested caffeine (250 mg) or placebo in random double-blind order. TheW _max was determined using a force-velocity exercise test. In addition, we measured blood lactate concentration for each load at the end of pedalling and after 5 min of recovery. We observed that caffeine increasedW _max [964 (SEM 65.77) W with caffeine vs 903.7 (SEM 52.62) W with placebo;P<0.02] and blood lactate concentration both at the end of pedalling [8.36 (SEM 0.95) mmol · l^–1 with caffeine vs 7.17 (SEM 0.53) mmol · l^–1 with placebo;P<0.011 and after 5 min of recovery [10.23 (SEM 0.97) mmol · l^–1 with caffeine vs 8.35 (SEM 0.66) mmol · l^–1 with placebo;P<0.04]. The quotient lactate concentration/power (mmol · l^–1 · W^–1) also increased with caffeine at the end of pedalling [7.6 · 10^–3 (SEM 3.82 · 10^–5) vs 6.85 · 10^–3 (SEM 3.01 · 10^–5);P<0.01] and after 5 min of recovery [9.82·10^–3 (SEM 4.28 · 10^–5) vs 8.84 · 10^–3 (SEM 3.58 · 10^–5);P<0.02]. We concluded that caffeine increased bothW _max and blood lactate concentration.     

Interference of strength development by simultaneously training for strength and endurance

Summary The purpose of this study was to determine how individuals adapt to a combination of strength and endurance training as compared to the adaptations produced by either strength or endurance training separately. There were three exercise groups: a strength group (S) that exercised 30–40 min·day^–1, 5 days·week^–1, an endurance group (E) that exercised 40 min·day^–1, 6 days·week^–1; and an S and E group that performed the same daily exercise regimens as the S and E groups. After 10 weeks of training, VO_{2 max} increased approx. 25% when measured during bicycle exercise and 20% when measured during treadmill exercise in both E, and S and E groups. No increase in VO_{2 max} was observed in the S group. There was a consistent rate of development of leg-strength by the S group throughout the training, whereas the E group did not show any appreciable gains in strength. The rate of strength improvement by the S and E group was similar to the S group for the first 7 weeks of training, but subsequently leveled off and declined during the 9th and 10th weeks. These findings demonstrate that simultaneously training for S and E will result in a reduced capacity to develop strength, but will not affect the magnitude of increase in VO_{2 max}.This research was supported by a University of Illinois at Chicago Circle Research Board Grant and by a NIH Biomedical Research Support Grant (HEW RR07158-2) to the University of Illinois at Chicago Circle     

Effects of 12 weeks of aerobic exercise plus dietary restriction on body composition,resting energy expenditure and aerobic fitness in mildly obese middle-aged women

This study investigated the effects of 12 weeks of aerobic exercise plus voluntary food restriction on the body composition, resting metabolic rate (RMR) and aerobic fitness of mildly obese middle-aged women. The subjects were randomly assigned to exercise/diet (n = 17) or control (n = 15) groups. The exercise/diet group participated in an aerobic training programme, 45–60 min · day ^–1 at 50%–60% of maximal oxygen uptake (VO_2max), 3–4 days · week^–1, and also adopted a self-regulated energy deficit relative to predicted energy requirements (–1.05 MJ · day ^–1 to –1.14 MJ · day ^–1 ). After the regimen had been followed for 12 weeks, the body mass of the subjects had decreased by an average of 4.5 kg, due mainly to fat loss, with little change of fat free mass (m _ff). The absolute RMR did not change, but the experimental group showed significant increases in the RMR per unit of body mass (10%) and the RMR per unit of m _ff (4%). The increase in RMR/m _ff was not correlated with any increase in VO_2max/m _ff. The resting heat production per unit of essential body mass increased by an average of 21%, but the resting heat production rate per unit of fat tissue mass remained unchanged. We concluded that aerobic exercise enhances the effect of moderate dietary restriction by augmenting the metabolic activity of lean tissue.     

Uniqueness of interval and continuous training at the same maintained exercise intensity

Summary The present study sought to evaluate the inconsistencies previously observed regarding the predominance of continuous or interval training for improving fitness. The experimental design initially equated and subsequently maintained the same relative exercise intensity by both groups throughout the program. Twelve subjects were equally divided into continuous (CT, exercise at 50% maximal work) or interval (IT, 30 s work, 30 s rest at 100% maximal work) training groups that cycled 30 min day^–1, 3 days week^–1, for 8 weeks. Following training, aerobic power (VO_2max), exercising work rates, and peak power output were all higher (9–16%) after IT than after CT (5–7%). Vastus lateralis muscle citrate synthase activity increased 25% after CT but not after IT. A consistent increase in adenylate kinase activity (25%) was observed only after IT. During continuous cycling testing the CT group had reduced blood lactate (1a_b) levels and respiratory quotient at both the same absolute and relative (70% VO_2max) work rates after training, while the IT group displayed similar changes only at the same absolute work rates. By contrast, both groups responded similarly during intermittent cycling testing with lower 1a_b concentrations seen only at absolute work rates. These results show that, of the two types of training programs currently employed, IT produces higher increases in VO_2max and in maximal exercise capacity. Nevertheless, CT is more effective at increasing muscle oxidative capacity and delaying the accumulation of 1a_b during continuous exercise.     

The influence of body position on maximal performance in cycling

Summary Six healthy male subjects performed a 3-min supramaximal test in four different cycling positions: two with different trunk angles and two with different saddle-tube angles. Maximal power output and maximal oxygen uptake (VO_2max) were measured. Maximal power output was significantly higher in a standard sitting (SS, 381 W, SD 49) upright position compared to all other positions: standard racing (SR, 364 W, SD 49), recumbent backwards (RB, 355 W, SD 44) and recumbent forwards (RF, 341 W, SD 54). Although VO_2max was also highest in SS (4.31 l · min^–1, SD 0.5) upright position, the differences in VO_2max were not significant (SR, 4.21 · min^–1, SD 0.53; RB, 4.17 l · min^–1, SD 0.58; RF, 4.11 l · min^–1, SD 0.66). It is concluded that (supra)maximal tests on a cycle ergometer should be performed in a sitting upright position and not in a racing position. In some cases when cycling on the road, higher speeds can be attained when sitting upright. This is especially true when cycling uphill when high power must be generated to overcome gravity but the road speed, and hence the power required to overcome air resistance, is relatively low.     

Effect of an iron supplement on body iron status and aerobic capacity of young training women

Summary Serum iron deficiency has a high incidence in female athletes. We investigated the effects of a daily oral iron supplement, (160 mg) administered during an intensive 7-week physical training programme, on body iron status, and the maximal aerobic capacity (VO_2max) of 13 women (group A) compared to 15 who took a placebo (group B). The subjects were 19 years old. Blood samples were obtained before training began and on days 1, 7, 21 and 42 of training. They were analysed for packed cell volume (PVC) and for haemoglobin (Hb), 2,3-diphosphoglycerate (2,3-DPG), haptoglobin, iron and ferritin concentrations. TheVO_2max was measured on days 0, 21 and 42 of training. Following 21 days of training Hb, PCV and ferritin were significantly higher (P0.01) in group A compared to group B. Over the training period Hb rose by 9.3% and 2.4% in groups A and B, respectively. At the end of training 66% of group B exhibited ferritin concentrations below 10 ng·ml^–1, while none of group A had such low values. MeanVO_2max of group A had increased by 7.5% following 21 days of training (P0.01) and by 15.3% after 42 days. No appreciable increase inVO_2max had occurred in group B by day 21 (significantly lower thanVO_2max of group A;P0.05), however by day 42 it had increased by 14.3% (P0.05). In both groups 2,3-DPG·g Hb^–1 had increased significantly (P0.005) by day 7 (22%) and remained at that level for an additional 35 days. We concluded that a daily oral iron supplement given to young women during intensive training improved several haematological variables and their body iron status. This improvement was associated with an increasedVO_2max only during the early stages of their training (day 21) compared with the placebo group.     

Endurance and neuromuscular changes in world-class level kayakers during a periodized training cycle

This study was undertaken to analyze changes in selected cardiovascular and neuromuscular variables in a group of elite kayakers across a 12-week periodized cycle of combined strength and endurance training. Eleven world-class level paddlers underwent a battery of tests and were assessed four times during the training cycle (T0, T1, T2, and T3). On each occasion subjects completed an incremental test to exhaustion on the kayak-ergometer to determine maximal oxygen uptake (VO_2max), second ventilatory threshold (VT2), peak blood lactate, paddling speed at VO_2max (PS_max) and at VT2 (PS_VT2), stroke rate at VO_2max and at VT2, heart rate at VO_2max and at VT2. One-repetition maximum (1RM) and mean velocity with 45% 1RM load (V _45%) were assessed in the bench press (BP) and prone bench pull (PBP) exercises. Anthropometric measurements (skinfold thicknesses and muscle girths) were also obtained. Training volume and exercise intensity were quantified for each of three training phases (P1, P2, and P3). Significant improvements in VO_2max (9.5%), VO₂ at VT2 (9.4%), PS_max (6.2%), PS_VT2 (4.4%), 1RM in BP (4.2%) and PBP (5.3%), V _45% in BP (14.4%) and PBP (10.0%) were observed from T0 to T3. A 12-week periodized strength and endurance program with special emphasis on prioritizing the sequential development of specific physical fitness components in each training phase (i.e. muscle hypertrophy and VT2 in P1, and maximal strength and aerobic power in P2) seems effective for improving both cardiovascular and neuromuscular markers of highly trained top-level athletes.     

The role of anaerobic ability in middle distance running performance

Summary The purpose of this study was to assess the relationship between anaerobic ability and middle distance running performance. Ten runners of similar performance capacities (5 km times: 16.72, SE 0.2 min) were examined during 4 weeks of controlled training. The runners performed a battery of tests each week [maximum oxygen consumption (VO_2max), vertical jump, and Margaria power run] and raced 5 km three times (weeks 1, 2, 4) on an indoor 200-m track (all subjects competing). Regression analysis revealed that the combination of time to exhaustion (TTE) during theVO_2max test (r ²=0.63) and measures from the Margaria power test (W·kg^–1,r ²=0.18 ; W,r ²=0.05) accounted for 86% of the total variance in race times (P<0.05). Regression analysis demonstrated that TTE was influenced by both anaerobic ability [vertical jump, power (W·kg^–1) and aerobic capacity (VO_2max, ml·kg^–1·min^–1)]. These results indicate that the anaerobic systems influence middle distance performance in runners of similar abilities.     

Treadmill validation of an over-ground walking test to predict peak oxygen consumption

Summary The purpose of this study was to determine whether a test developed to predict maximal oxygen consumption (VO_2max) during over-ground walking, was similarly valid as a predictor of peak oxygen consumption (VO₂) when administered during a 1-mile (1.61 km) treadmill walk. Treadmill walk time, mean heart rate over the last 2 full min of the walk test, age, and body mass were entered into both generalized (GEN Eq.) and gender-specific (GSP Eq.) prediction equations. Overall results indicated a highly significant linear relationship between observed peakVO₂ and GEN Eq. predicted values (r=0.91), a total error (TE) of 5.26 ml · kg^–1 · min^–1 and no significant difference between observed and predicted peakVO₂ mean values. The peakVO₂ for women (n = 75) was predicted accurately by GSP Eq. (r = 0.85; TE = 4.5 ml · kg^–1 · min^–1), but was slightly overpredicted by GEN Eq. (overall mean difference = 1.4 ml · kg^–1 · min^–1;r=0.86; TE = 4.56 ml · kg^–1 · min^–1). No significant differences between observed peakVO₂ and either GEN Eq. (r=0.85; TE=4.3 ml · kg^–1 · min^–1) or GSP Eq. (r=0.85; TE = 4.8 ml · kg^–1 · min^–1)predicted values were noted for men (n=48) with peakVO₂ values less than or equal to 55 ml · kg^–1 · min^–1. However, both equations significantly underpredicted peakVO₂ for the remaining high peakVO₂ men (n = 22). In conclusion, the over-ground walking test, when administered on a treadmill, is a valid method of predicting peakVO₂ but underpredicts peakVO₂ of subjects with observed high peakVO₂ values. Present address: Human Performance Laboratory State University, Muncie, IN 47306, USA     

Magnitude and time course of changes in maximal oxygen uptake in response to distinct regimens of chronic interval training in sedentary women

Purpose

This study aimed to compare changes in maximal oxygen uptake (VO_2max) in response to two regimens of chronic interval training.

Methods

Twenty healthy sedentary women (mean ± SD age and VO_2max = 23.0 ± 5.7 years and 30.1 ± 4.4 mL kg^?1 min^?1, respectively) were randomized to complete 12 weeks of one of two interval training regimes, while an additional seven women served as controls. Training was performed 3 days week^?1 on a cycle ergometer and consisted of 6–10 bouts of 1 min duration at lower (60–80 % W _max = LO, n = 10) or more intense (80–90 % W _max = HI, n = 10) workloads separated by a brief recovery. Every 3 weeks, measures of VO_2max and W _max were repeated to assign new training intensities. Changes in blood pressure and body composition were also examined.

Results

Data revealed significant (p < 0.001) improvements in VO_2max in LO (22.3 ± 6.9 %) and HI (21.9 ± 11.6 %) that were similar (p > 0.05) between groups. Approximately 60 % of the increase in VO_2max in HI was observed in the initial 3 weeks, compared to only 20 % in LO. No change (p > 0.05) in body weight or body composition was revealed in response to training. Results demonstrate that a relatively prolonged regimen of moderate or more intense interval training induces similar improvements in cardiorespiratory fitness, although HI induced greater increases in VO_2max early on in training than LO. Completion of more intense interval training may be an effective means to expedite increases in VO₂max soon after initiation of exercise training.     

Energy cost and energy sources in karate

Energy costs and energy sources in karate (wado style) were studied in eight male practitioners (age 23.8 years, mass. 72.3 kg, maximal oxygen consumption (VO_2max) 36.8 ml · min^–1 · kg^–1) performing six katas (formal, organized movement sequences) of increasing duration (from approximately. 10 s to approximately 80 s). Oxygen consumption (VO₂) was determined during pre-exercise rest, the exercise period and the first 270 s of recovery in five consecutive expired gas collections. A blood sample for lactate (la^–) analysis was taken 5 min after the end of exercise. The overall amount of O₂ consumed during the exercise and in the following recovery increased linearly with the duration of exercise (t) from approximately 1.51 (for t equal to 10.5 s (SD 1.6)) to approximately 5.81, for t equal to 81.5 s (SD 1.0). The energy release from la^– production (VO_21a ^–) calculated assuming that an increase of 1 mmol · l^–1 la^– corresponded to a VO₂ of 3 mlO₂ · kg^–1 was negligible for t equal to or less than 20 s and increased to 17.3 ml · kg^–1 (la^– = 5.8 mmol · l^–1 above resting values) for t equal approximately to 80 s. The overall energy requirement (VO_2eq) as given by the sum of VO₂ and VO_2la ^– was described by VO_2eq = 0.87 + 0.071 · t (n = 64; r ² = 0.91), where VO_2eq is in litres and t in seconds. This equation shows that the metabolic power (VO_2eq · t ^–1) for this karate style is very high: from approximately 9.51 · min^–1 for t equal to 10 s to approximately 4.91 · min^–1 for t equal to 80 s, i.e. from 3.5 to 1.8 times the subjects' VO_2max. The fraction of VO_2eq derived from the amount of O₂ consumed during the exercise increased from 11% for t equal to 10 s to 41 % for t equal to 80 s whereas VO_21a ^– was negligible far t equal to or less than 20 s and increased to 13 % o for t equal to 80 s. The remaining fraction (from 90% for t equal to 10 s to 46% for t equal to 80 s), corresponding to the amount of O₂ consumed in the recovery after exercise, is derived from anaerobic alactic sources, i.e. from net splitting of high energy phosphates during the exercise.     

V O 2 kinetics in subjects differing in aerobic capacity: investigation by spectral analysis

Summary The power-V _{O 2} transfer functions of 38 subjects differing in aerobic capacity have been determined on the basis of breath-by-breath total oxygen uptake (V _{O 2.1}) measurements during light cycle ergometer exercise (lactic acid concentrations below 2 mmol · l^–1). At constant pedalling frequency (1 Hz) pseudorandom binary sequences (PRBS) of workload were used as the testing signal. TheV _{O 2.1} response was analysed by autocorrelating the ergometer power input and crosscorrelating the power input andV _{O 2.1} output. From the spectra of these functions the amplitude ratios and phase relationships were computed for the first six harmonics of the PRBS fundamental (14 mrad · s^–1). We found that differences in aerobic capacity are associated with significant differences in the amplitude plots of theV _{O 2} transfer function.     

Increase in maximal oxygen uptake following 2-week walk training with blood flow occlusion in athletes

Walk training with blood flow occlusion (OCC-walk) leads to muscle hypertrophy; however, cardiorespiratory endurance in response to OCC-walk is unknown. Ischemia enhances the adaptation to endurance training such as increased maximal oxygen uptake ( V\textO _{2 max} V{\text{O}}_{{ 2_{ \max } }} ) and muscle glycogen content. Thus, we investigated the effects of an OCC-walk on cardiorespiratory endurance, anaerobic power, and muscle strength in elite athletes. College basketball players participated in walk training with (n = 7) and without (n = 5) blood flow occlusion. Five sets of a 3-min walk (4–6 km/h at 5% grade) and a 1-min rest between the walks were performed twice a day, 6 days a week for 2 weeks. Two-way ANOVA with repeated measures (groups × time) was utilized (P < 0.05). Interactions were found in V\textO _{2 max} V{\text{O}}_{{ 2_{ \max } }} (P = 0.011) and maximal minute ventilation (VE_max; P = 0.019). V\textO _{2 max} V{\text{O}}_{{ 2_{ \max } }} (11.6%) and VE_max (10.6%) were increased following the OCC-walk. For the cardiovascular adaptations of the OCC-walk, hemodynamic parameters such as stroke volume (SV) and heart rate (HR) at rest and during OCC-walk were compared between the first and the last OCC-walk sessions. Although no change in hemodynamics was found at rest, during the last OCC-walk session SV was increased in all five sets (21.4%) and HR was decreased in the third (12.3%) and fifth (15.0%) sets. With anaerobic power an interaction was found in anaerobic capacity (P = 0.038) but not in peak power. Anaerobic capacity (2.5%) was increased following the OCC-walk. No interaction was found in muscle strength. In conclusion, the 2-week OCC-walk significantly increases V\textO _{2 max} V{\text{O}}_{{ 2_{ \max } }} and VE_max in athletes. The OCC-walk training might be used in the rehabilitation for athletes who intend to maintain or improve endurance.     

Ventilatory threshold and work efficiency during exercise on cycle and paddling ergometers in young female kayakists

The aim of this study was to assess the effects of increasing specific (paddling erogmeter) and non-specific (cycle ergometer) exercise on parameters relating to the ventilatory threshold (Th_vent) and work efficiency in 11 young female flat-water kayakists. When these trained subjects were tested using non-specific workloads, their oxygen uptake (VO₂) values at Th_vent, as a percentage ofVO_2max (%VO_2max), were close to those of untrained subjects [74.2 (5.6) %VO_2max, mean (SD)]. However, when we tested the same subjects using specific exercise, we recorded values typical of highly trained athletes [84.8 (4.7) %VO_2max). For the non-specific exercise on the cycle erogmeter, we recorded work efficiency values close to those of untrained subjects [22.3 (2.5) %]; however, for the specific exercise on the paddling ergometer, we recorded much lower values [13.4 (3.0) %] both at the level of Th_vent. The work efficiency at two warm-up submaximal exercise loads on the paddling ergometer was non-significantly lower than values at Th_vent [12.3 (2.8) % and 12.9 (2.9) % respectively]. Significant correlations were found between maximal-performanceVO₂ (ml · kg^–1 · min^–1) and performance at Th_vent during paddling and race performance (0.623, 0.630 and 0.648 respectively, allP<0.05). Because the results of both specific and non-specific submaximal exercise tests are different, we suggest caution in the interpretation of physiological variables that may be sensitive to training status. The evaluation of Th_vent and work efficiency as supplementary parameters during laboratory studies enables the determination of the effectiveness of the training process and the specific adaptation of the subjects.     

Early adaptations in gas exchange,cardiac function and haematology to prolonged exercise training in man

Summary In order to determine the effect of shortterm training on central adaptations, gas exchange and cardiac function were measured during a prolonged submaximal exercise challenge prior to and following 10–12 consecutive days of exercise. In addition, vascular volumes and selected haematological properties were also examined. The subjects, healthy males between the ages of 19 and 30 years of age, cycled for 2 h per day at approximately 59% of pre-training peak oxygen consumption (VO₂) i.e., maximal oxygen consumption (VO_{2 max}). Following the training,VO_{2 max} (1·min^–1) increased (P<0.05) by 4.3% (3.94, 0.11 vs 4.11, 0.11; mean, SE) whereas maximal exercise ventilation (V _E,max) and maximal heart rate (_c,max) were unchanged. During submaximal exercise,VO₂ was unaltered by the training whereas carbon dioxide production (V _E) and respiratory exchange ratio were all reduced (P<0.05). The altered activity pattern failed to elicit adaptations in either submaximal exercise cardiac output or arteriovenous O₂ difference. _c was reduced (P<0.05). Plasma volume (PV) as measured by¹²⁵I human serum albumin increased by 365 ml or 11.8%, while red cell volume (RCV) as measured by⁵¹chromium-labelled red blood cells (RBC) was unaltered. The increase in PV was accompanied by reductions (P<0.05) in haematocrit, haemoglobin concentration (g. 100 ml^–1), and RBCs (10⁶ mm^–3). Collectively these changes suggest only minimal adaptations in maximal oxygen transport during the early period of prolonged exercise training. However, as evidenced by the changes during submaximal exercise, both the ventilatory and the cardiodynamic response were altered. Since RCV did not change, it is suggested that the elevated PV accompanying training is instrumental in eliciting the change in cardiac function.     

Prediction of <Emphasis Type="Italic">V</Emphasis>O<Subscript>2max</Subscript> with daily step counts for Japanese adult women

The purpose of the study was to develop a new non-exercise VO_2max prediction model using a physical activity (PA) variable determined by pedometer-determined step counts (SC, steps day⁻¹) in Japanese women aged 20–69 years old. Eighty-seven and 102 subjects were used to develop the prediction model, and to validate the new model, respectively. VO_2max was measured using a maximal incremental test on a bicycle ergometer. SC was significantly related to VO_2max (partial correlation coefficient r = 0.40, P < 0.001) after adjusting for BMI (kg m⁻²) and age (years). When the new prediction equation developed by multiple regression to estimate VO_2max from age, BMI, and SC (R = 0.71, SEE = 5.3 ml kg⁻¹ min⁻¹, P < 0.001) was applied to the Validation group, predicted VO_2max correlated well with measured VO_2max (r = 0.81, P < 0.001), suggesting that SC is a useful PA variable for non-exercise prediction of VO_2max in Japanese women.