Nine months aerobic fitness induced changes on blood lipids and lipoproteins in untrained subjects versus controls

Regular endurance exercise has favorable effects on cardiovascular risk factors. However, the impact of an exercise-induced change in aerobic fitness on blood lipids is often inconsistent. The purpose of this study was to investigate the effect of nine consecutive months of training on aerobic fitness and blood lipids in untrained adults. Thirty subjects 35-55 years of age (wt: 73.1 +/- 13.6 kg, height 171.1 +/- 9.0 cm, %body fat 24.6 +/- 6.3%, 14 males and 16 females) were randomly assigned to an exercise (EG) (N = 20) and control (CG) (N = 10) group. All subjects completed an incremental treadmill test, anthropometric measurements, and venous blood sample collection before and after the 9 months of exercise. Participants in the exercise group were supervised and adjusted for improvements in running performance, whereas no change was administered for the control group. One-way and multivariate ANOVA was conducted to determine significant differences in means for time and group in selected variables [body mass, % body fat, BMI; VO(2peak), km/h at 2.0 (v-LA2) and 4.0 (v-LA4) mmol l(-1) blood lactate (LA) concentration, km/h of the last load (v-max); TC, LDL-C, HDL-C, TG, Apo B, Apo A-1, and Lp (a)]. Correlation coefficients and multivariate regression analysis was used to determine the association between aerobic fitness and blood lipids. The exercise group improved significantly (P < 0.0001) in VO(2peak), v-LA2, v-LA4, v-max and exhibited a significant decrease in Apo B (P < 0.04) compared to the control group (NS). In 9 months, E achieved 24% increase in VO(2peak) and 18% reduction in Apo B, denoting the impact of cardiovascular fitness on cardiovascular risk.     

Effects of explosive type strength training on physical performance characteristics in cross-country skiers

Summary To investigate the effects of a combination of simultaneous strength and endurance training on selected neuromuscular and aerobic performance characteristics seven male cross-country skiers underwent training for a period of 6 weeks. The experimental group trained 6–9 times per week with a programme consisting of 34% explosive type strength training and 66% endurance training during the first 3 weeks of the experiment and 42% and 58% respectively during the last 3 weeks of the experiment. The total volume of training of the control group (eight skiers) was of the same magnitude but consisted of 85% pure endurance training and 15% endurance type strength training. The experimental training regime resulted in specific changes in neuromuscular performance. This was demonstrated by improvements (P<0.01) in the maximal heights of rise of the centre of gravity in the squat and countermovement jumps. A significant decrease (P<0.05) took place also in the time of rapid isometric force production during experimental training, while no changes occurred in the maximal force of the trained muscles. Aerobic performance characteristics of the experimental group did not change during the experimental training period. No significant changes occurred in neuromuscular or aerobic performance characteristics in the control group. These findings indicated that training-induced improvements in explosive force production may not be fully inhibited by this kind of aerobic training. They also suggested that endurance athletes could undertake explosive type strength training programmes without a concomitant reduction in aerobic capacity, if the overall loading of training were within predefined limits.     

Influence of heat stress and acclimation on maximal aerobic power

Summary Thirteen male volunteers performed cycle ergometer maximal oxygen uptake ( tests) in moderate (21 C, 30% rh) and hot (49 C, 20% rh) environments, before and after a 9-day heat acclimation program. This program resulted in significantly decreased (P<0.01) final heart rate (24 bt·min^–1) and rectal temperature (0.4 C) from the first to last day of acclimation. The was lower (P<0.01) in the hot environment relative to the moderate environment both before (8%) and after (7%) acclimation with no significant difference (P>0.05) shown for maximal power output (PO max, watts) between environments either before or after acclimation. The was higher (P<0.01) by 4% after acclimation in both environments. Also, PO max was higher (P<0.05) after acclimation in both the moderate (4%) and hot (2%) environments. The reduction in in the hot compared to moderate environment was not related to the difference in core temperature at between moderate and hot trials, nor was it strongly related with aerobic fitness level. These findings indicate that heat stress, per se, reduced the . Further, the reduction in due to heat was not affect be state of heat acclimation, the degree of elevation in core temperature, or level of aerobic fitness.     

Energy system contribution in a maximal incremental test: correlations with pacing and overall performance in a 10-km running trial

This study aimed to verify the association between the contribution of energy systems during an incremental exercise test (IET), pacing, and performance during a 10-km running time trial. Thirteen male recreational runners completed an incremental exercise test on a treadmill to determine the respiratory compensation point (RCP), maximal oxygen uptake (V˙O2max), peak treadmill speed (PTS), and energy systems contribution; and a 10-km running time trial (T10-km) to determine endurance performance. The fractions of the aerobic (W_AER) and glycolytic (W_GLYCOL) contributions were calculated for each stage based on the oxygen uptake and the oxygen energy equivalents derived by blood lactate accumulation, respectively. Total metabolic demand (W_TOTAL) was the sum of these two energy systems. Endurance performance during the T10-km was moderately correlated with RCP, V˙O2maxand PTS (P<@0.05), and moderate-to-highly correlated with W_AER, W_GLYCOL, and W_TOTAL (P<0.05). In addition, W_AER, W_GLYCOL, and W_TOTAL were also significantly correlated with running speed in the middle (P<0.01) and final (P<0.01) sections of the T10-km. These findings suggest that the assessment of energy contribution during IET is potentially useful as an alternative variable in the evaluation of endurance runners, especially because of its relationship with specific parts of a long-distance race.     

Influence of fluid intake on endurance running performance

Summary The aim of the present study was to compare the influence of drinking water, a carbohydrate-electrolyte solution, containing additional free glucose (Glucose) or the same carbohydrate-electrolyte solution containing additional fructose (Fructose), on running performance. Twelve endurance-trained recreational runners volunteered to take part in this study; 9 completed the three and all 12 completed two trials. The subjects were randomly assigned to one of the three trials: Water, Glucose or Fructose. In each trial the subjects were required to run 30 km as fast as possible on a motorized treadmill, instrumented so that they could control its speed. The carbohydrate-electrolyte solutions contained a total of 50 g carbohydrate, 20 g as a glucose polymer. The Glucose solution contained an additional 20 g free glucose and the Fructose solution contained an additional 20 g fructose rather than glucose. The osmolality of the Glucose and Fructose solutions was approximately 300–320 mosmol and the energy equivalent of both solutions was 794 kJ·l^–1. The subjects ingested 11 fluid throughout each run. The running times were not significantly different, being 129.3 (±17.7) min, 124.8 (±14.9) min and 125.9 (±17.9) min for Water, Glucose and Fructose respectively. There was a decrease (P<0.05) in running speed over the last 10 km of the Water trial from 4.14 (±0.55) to 3.75 (±0.86) m· s^–1, which did not occur in the carbohydrate trials. Blood glucose concentrations during the Water trial decreased from 15 km onwards and at the end of the run they were significantly (P<0.05) lower than the value recorded at 15 km. In contrast they did not decrease in the two carbohydrate trials. There were no significant differences between the responses of the subjects during the Glucose and Fructose trials.     

Changes in maximal aerobic power,aerobic capacity,and muscle enzyme activities at two stages of the annual training cycle in ski-runners

Summary Changes of cardiorespiratory capacity, of the activity of seven enzymes involved in energy metabolism and of laboratory endurance were investigated in a group of nine male ski-runners before and after exhausting training and a competing period during the winter.Despite the decrease in laboratory endurance and total work oxygen consumption between the investigations, O₂ max, O₂-pulse max and O₂ debt did not change; and O₂-pulse per kg b.w. showed a significant increase.In biopsy samples of the vastus lateralis muscle, the activity of enzymes of carbohydrate metabolism, both anaerobic and total (triose phosphate dehydrogenase — TPDH, lactate dehydrogenase — LDH, hexokinase — HK), and of total aerobic metabolism (citrate synthetase — CS, malate dehydrogenase — MDH), was decreased during this period by 27 to 59% (mean values for different enzymes). The mean activity of cytoplasmic glycerol phosphate dehydrogenase (GPDH) and of hydroxyacyl — CoA dehydrogenase (HOADH) did not change, although the activity of the latter enzyme was decreased in the muscle of those ski-runners who were trained predominantly for speed, and it was increased in those trained mainly for endurance.The changes in activity of the muscle enzymes associated with glycolysis (TPDH and LDH) and of MDH, connected with metabolism and hydrogen transport between cytoplasmic and aerobic mitochondrial compartments, correlate inversely with those of aerobic capacity (total work O₂ consumption).     

The influence of high carbohydrate diets on endurance running performance

Summary The purpose of the present study was to examine the influence of high carbohydrate (CHO) diets on recovery of endurance capacity following a treadmill run to exhaustion. Two high CHO diets were used, one in which the normal diet was supplemented with complex carbohydrates and the other in which supplementation was achieved with simple carbohydrates. The thirty recreational runners who took part in this study (fifteen men and fifteen women) completed weighed food intake diaries two to three weeks before the start of the study. From an analysis of this information each subject's normal diet was prescribed before Trial 1 and then a supplemented diet before Trial 2. The aim was to achieve an increase in carbohydrate content to 70% in the diets of the two high CHO groups and an equivalent increase in energy intake by the Control group. The subjects were required to run to exhaustion on a treadmill at a speed equivalent to 70% on two occasions separated by 3 days. After Trial 1 the subjects were divided into three equal groups. The Complex CHO group (301±86 mg vs 507±120 mg) and Simple CHO group (265±45 mg vs 462±81 mg) increased their CHO intake by approximately 70% (p<0.05) during the 3 days before Trial 2 whereas the Control group increased their energy intake with additional protein and fat so as to match the energy intakes of the two CHO groups. The Complex CHO group improved their running time to exhaustion during Trial 2 by 26% (105.9±22.4 to 133.3±46.5 min;p<0.01) and the Simple CHO group increased their run time by 23% (114.5±15.6 to 140.6±27.0 min;p<0.01) whereas there was no significant increase in the running time of the Control group (119±19.5 to 122.4±22.4 min). There was no significant difference between the blood lactate and glucose concentrations during the two trials but the plasma FFA concentrations were significantly lower before Trial 2 for the Complex CHO group (0.41±0.15 vs 0.27±0.16 mmol^–1;p<0.01) and the Simple CHO group (0.24±0.13 vs 0.19±0.09 mmol^–1). The respiratory exchange ratios for the two CHO groups were significantly higher for most of Trial 2 compared with the values obtained during Trial 1. The results of this study have shown that recovery of endurance running capacity is enhanced by an increase in dietary CHO, which can be accomplished by supplementing the normal diet with either simple or complex carbohydrates.     

Effects of intermittent hypoxic training on cycling performance in well-trained athletes

This study aimed to investigate the effects of a short-term period of intermittent hypoxic training (IHT) on cycling performance in athletes. Nineteen participants were randomly assigned to two groups: normoxic (NT, n = 9) and intermittent hypoxic training group (IHT, n = 10). A 3-week training program (5 × 1 h–1 h 30 min per week) was completed. Training sessions were performed in normoxia (∼30 m) or hypoxia (simulated altitude of 3,000 m) for NT and IHT group, respectively. Each subject performed before (W0) and after (W4) the training program, three cycling tests including an incremental test to exhaustion in normoxia and hypoxia for determination of maximal aerobic power and peak power output (PPO) as well as a 10-min cycle time trial in normoxia (TT) to measure the average power output (P _aver). No significant difference in was observed between the two training groups before or after the training period. When measured in normoxia, the PPO significantly increased (P < 0.05) by 7.2 and 6.6% in NT and IHT groups, respectively. However, only the IHT group significantly improved (11.3%; P < 0.05) PPO when measured in hypoxia. The NT group improved (P < 0.05) P _aver in TT by 8.1%, whereas IHT group did not show any significant difference. Intermittent training performed in hypoxia was less efficient for improving endurance performance at sea level than similar training performed in normoxia. However, IHT has the potential to assist athletes in preparation for competition at altitude.     

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.     

Ergogenic effect of varied doses of coffee-caffeine on maximal aerobic power of young African subjects

Background

Caffeine one of the readily available stimulants consumed daily by more than 80% of the world''s population, making it the most widely consumed drug in history. The objective of this study was to determine the effects of different doses (5, 10 &15 mg.kg⁻¹) of caffeine per kilogram body weight on maximal aerobic power of normal young black African (Nigerian) male adults.

Method

Twenty apparently healthy young male adults volunteers, participated. A repeated measure four randomized crossover (counter balanced) double blind design was used in data collection. Subjects engaged in 20 meter shuttle run test (20 MST) one hour post caffeine (5, 10 & 15 mg.kg⁻¹) and placebo doses ingestion. Endurance performance index (VO₂ max, run time & number of exercise laps) were measured and recorded.

Result

Repeated measures ANOVA was used to assess the level of significant difference between caffeine doses and placebo dose in VO₂ max, run time and number of exercise laps. The result showed no significant effect of caffeine doses over placebo dose.

Conclusion

It was concluded that caffeine dose of up to 15mg/kg seems not to have any ergogenic effect on maximum aerobic power of young black African male adults.     

Changes in fitness and shipboard task performance following circuit weight training programs featuring continuous or interval running

Summary Pre- and post-physiological data were collected on 57 Navy men (¯x age=19.5 years) who participated in either circuit weight training/ continuous run (CWT/CR) (N=31) or circuit weight training/interval run (CWT/IR) (N=26) programs. Measured variables included 4 measures of upper torso dynamic strength (one repetition maximum [1RM] for arm curl, bench press, shoulder press, and lat pull-down); two measures of lower torso dynamic strength (1RM) for knee extension and leg press); one measure of power (number of revolutions completed on an arm ergometer (Monark^®) at maximum drag); three measures of muscular endurance (number of repetitions at 60% 1RM for bench press and leg press and maximal number of bent-knee sit-ups in 120 s); one stamina measure (time to exhaustion on a cycle ergometer (Monark^®) maximal work capacity [MWC] test; and three simulated shipboard tasks: manikin shoulder drag, open/secure a water tight door and paint bucket carry. Composite shipboard performance derived from the summed time (s) required to complete the three tasks was also calculated. Results show performance on the manikin shoulder drag and majority of evaluative fitness measures was significantly (p<0.05) enhanced following both circuit weight training/run formats. Significantly (p<0.05) higher values for shoulder press (F=7.2), arm ergometer (F=5.3), and sit-ups (F=6.8) and lower values for leg press muscular endurance (F=5.1) were observed in CWT/IR when compared to CWT/CR. Regression analysis yielded the following prediction equation: Composite shipboard performance (s)=194.15097-1.59492 (arm curl) -0.18369 (leg press)r=0.74.It can be concluded that exercise participation was associated with differential changes in fitness but not job performance. Furthermore, the association between fitness gains and job criteria performance appeared to be specific to the task modelled. Important predictors of criterion task performance included parameters of upper torso and lower torso muscular strength.Report No. 85-33 was supported by the Naval Medical Research and Development Command, Department of the Navy, under research Work Unit M0096-PN.001-1050. The views presented in this paper are those of the authors. No endorsement by the Department of the Navy has been given or should be inferred     

The effect of an α-ketoglutarate-pyridoxine complex on human maximal aerobic and anaerobic performance

Summary The administration of 30 mg/kg of body weight of an -ketoglutarate-pyridoxine complex (-KG compl; stoichiometric ratio -KG: pyridoxine 46.35 to 53.65) to trained non-athletic individuals increases max by 6% (p<0.005). The kinetics of the on- and off-responses at the onset and offset of a rectangular work load is not affected by the drug. Peak blood lactate concentration [La_b] following two supramaximal running work loads lasting 60 s and 132±4 s, respectively is significantly (p<0.05 and p<0.005) less after the -KG compl treatment (La_b=–1.1 and –2.7 mmol·1^–1, respectively) than in a control group. The half time (t1/2) of La disappearance from blood during recovery is unaffected by the -KG compl treatment (19.7 min vs 19.5 min). The increase in max and the corresponding decrease of [La_b] are not found after separate administration of either of the components of the complex. It is concluded that -KG complex stimulates aerobic metabolism, probably prompting mitochondrial reabsorption of -KG, which activates the malate-oxalacetate shuttle and the generation of high energy phosphates at the substrate level.     

The effect of O2 breathing on maximal aerobic power

Summary Time of performance, blood lactic acid concentration (L.A.), heart rate (H.R.) and maximal oxygen consumption ( ) were measured during air and oxygen breathin in 11 subjects performing a supramaximal exercise with an O₂ requirement of 70 to 80 ml/kg·min to exhaustion. In addition the subjects were tested for maximal aerobic power with an indirect method. In one subject the rate of lactic acid increase in blood was also measured.The measured with both the direct and the indirect method appears to be about 8% higher when breathing pure oxygen; lactic acid production rate decreases correspondingly. Maximal H.R. and maximal L.A. concentration were found to be the same.In submaximal exercise steady state H.R. is lower by about 8–9 beats/min when breathing oxygen. Also when breathing oxygen H.R. is a linear function of the work load.From experimental data obtained in subjects of different , breathing both air or O₂, the energy equivalent of L.A. could be calculated as amounting to about 47 ml of O₂ or 235 cal per g of L.A. produced.This work was supported by a grant from the National Research Council of Italy (C.N.R.)     

The effect of cycling followed by running on respiratory muscle performance in elite and competition triathletes

This study investigated the possibility of there being differences in respiratory muscle strength and endurance in elite and competition triathletes who have similar maximal oxygen uptakes (VO_2max) and ventilatory thresholds (Th_vent). Five internationally-ranked elite, [mean (SD) age 23.8 (1.4) years] and six nationally- and regionally-ranked competition [age 21.1 (1.1) years] male triathletes performed two successive trials: first an incremental cycle test to assess VO_2max and Th_vent and second 20 min of cycling followed by 20 min of running (C-R) at intensities higher than 85% VO_2max. Cardioventilatory data were collected every minute during the two trials, using an automated breath-by-breath system. Maximal expiratory and inspiratory (P _Imax) strength were assessed before and 10 min after C-R from the functional residual capacity. Respiratory muscle endurance was assessed 1 day before and 30 min after C-R by measuring the time limit (t _lim). The results showed firstly that during C-R, the competition triathletes had significantly (P<0.05) higher minute ventilation [mean (SEM) 107.4 (3.1) compared to 99.8 (3.7) l·min^–1], breathing frequency [44.4 (2.0) compared to 40.2 (3.4) ·min^–1] and heart rate [166 (3) compared to 159 (4) beats·min^–1] and secondly that after C-R, they had significantly lower P _Imax [127.1 (4.2) compared to 130.7 (3.0) cmH₂O] and t_lim [2:35 (0:29) compared to 4:12 (0:20) min] than the elite triathletes. We conclude that, despite similar VO_2max and Th_vent, the competition triathletes showed less extensive adaptive mechanisms, including those in the respiratory muscles, than did the elite triathletes. This led to higher ventilation, which appeared to be the cause of the faster development of fatigue in the inspiratory muscles in this group. Electronic Publication     

The highest intensity and the shortest duration permitting attainment of maximal oxygen uptake during cycling: effects of different methods and aerobic fitness level

The aims of this study were: (1) to verify the validity of previous proposed models to estimate the lowest exercise duration (T _LOW) and the highest intensity (I _HIGH) at which VO₂max is reached (2) to test the hypothesis that parameters involved in these models, and hence the validity of these models are affected by aerobic training status. Thirteen cyclists (EC), eleven runners (ER) and ten untrained (U) subjects performed several cycle-ergometer exercise tests to fatigue in order to determine and estimate T _LOW (ET _LOW) and I _HIGH (EI _HIGH). The relationship between the time to achieved VO₂max and time to exhaustion (T _lim) was used to estimate ET _LOW. EI _HIGH was estimated using the critical power model. I _HIGH was assumed as the highest intensity at which VO₂ was equal or higher than the average of VO₂max values minus one typical error. T _LOW was considered T _lim associated with I _HIGH. No differences were found in T _LOW between ER (170 ± 31 s) and U (209 ± 29 s), however, both showed higher values than EC (117 ± 29 s). I _HIGH was similar between U (269 ± 73 W) and ER (319 ± 50 W), and both were lower than EC (451 ± 33 W). EI _HIGH was similar and significantly correlated with I_HIGH only in U (r = 0.87) and ER (r = 0.62). ET _LOW and T _LOW were different only for U and not significantly correlated in all groups. These data suggest that the aerobic training status affects the validity of the proposed models for estimating I _HIGH.     

Effects of aerobic long distance running training (up to 40 km · day−1) of 1-year duration on blood and endocrine parameters of female beagle dogs

Summary The effects of long distance running training on blood parameters, hormone responses and bone growth were studied in young growing dogs. A genetically uniform group of female beagles matched with respect to age and body mass were used. The runner dogs (n=10) underwent gradually increased running exercise up to 40 km · day^–1 on a treadmill with 15° uphill gradient 5 days each week during a period of 1 year, while the littermate control dogs (n=10) were kept in their cages throughout the study. Low plasma lactate concentrations of the runners measured immediately after the running training indicated the aerobic metabolism of the dogs while running. Significant decreases of blood haemoglobin concentrations (11%), blood erythrocyte number (10%), and erythrocyte packed cell volume (12%) were found in the runner group. Throughout the experiment, the value of thyroxine was slightly lower (13%) in the runners but no changes were found in tri-iodothyronine, free thyroxine, or cortisol serum concentrations. Serum oestradiol concentration at 56 weeks was significantly lower (42%) in the runner group than in the control group but was not as low (27%) at 70 weeks. Somatomedin-C concentration had decreased significantly by 37% at the age of 56 weeks in the runner group but was again at the level of the control dogs at the end of experiment (at 70 weeks). Ulna and radius bone mass as a ratio to the body mass had significantly increased in the runners. It would seem from our study that long distance running has a positive effect on bone growth. However, inadequate energy intake may have brought about lowered body mass with altered endocrine homeostasis, especially affecting oestradiol and somatomedin-C.     

Noninvasive determination of the anaerobic threshold in canoeing,cross-country skiing,cycling, roller,and iceskating,rowing, and walking

Summary The relationship between velocity (V) and heart rate (HR) was determined in four canoeists, 42 cross-country skiers, 73 cyclists, nine ice-skaters, 10 roller-skaters, 32 rowers, and 20 walkers. The athletes were asked to increase their work intensity progressively, from low to submaximal velocities; HRs were determined by ECG in roller-, ice-skating, and walking, or read on a cardiofrequency meter in canoeing, cross-country skiing, cycling, and rowing.In all the athletes examined the linearity of the V-HR relationship was maintained up to a submaximal speed (deflection velocity, V_d), beyond which the increase in work intensity exceeded the increase in HR.V_d and anaerobic threshold (AT), determined through blood lactate measurements, were coincident in 19 athletes (6 cross-country skiers, 3 cyclists, 2 roller-skaters, 3 rowers, and 5 walkers).V_d was correlated with the average speeds maintained in walking (20km, n=13, r=0.88), cross-country skiing (15 km, n=20, r=0.80; 30 km, n=8, r=0.82; 12 km, n=7, r=0.86; 11 km, n=7, r=0.86) and cycling (1,000 m flying-start, n=68, r=0.83), thus showing that AT is a limiting factor in these aerobic events.     

The relation of aerobic fitness to neuroelectric indices of cognitive and motor task preparation

The relation of aerobic fitness to task preparation was examined in a sample of young adults separated into higher‐ and lower‐fit groups according to their maximal oxygen consumption. Participants performed a modified Sternberg working memory task under speed and accuracy instructions while measures of task performance and contingent negative variation (CNV) were collected. Analyses revealed no significant fitness differences between groups on task performance measures. However, frontal CNV amplitude was significantly larger for lower‐fit participants compared to higher‐fit participants during the speed instructions, an effect not found for the accuracy instructions. These results suggest that lower‐fit individuals may rely to a greater extent on cognitive control processes to respond under speeded conditions, whereas higher‐fit individuals may maintain a more constant level of control irrespective of the task instructions.     

Influence of menopause on serum lipids and lipoproteins

The influence of the menopause on serum lipids and lipoproteins was examined longitudinally at 6-week intervals for 2–3 years in pre-menopausal women undergoing the menopause. Serum lipid and lipoprotein profiles were also examined cross-sectionally in 4 groups of pre-menopausal, perimenopausal and post-menopausal women, who were followed up longitudinally at 3-monthly examinations for 1–2 years. The results covering 1360 examinations and 270 woman-years are reported here.

Serum concentrations of total cholesterol (P = 0.001), low-density-lipoprotein (LDL) cholesterol (P = 0.001) and triglycerides (P < 0.05) increased significantly as a consequence of the menopause and all increases occurred within 6 months of cessation of menstrual periods. High-density-lipoprotein (HDL) cholesterol decreased significantly (P < 0.05) as a consequence of the menopause, but the decline occurred gradually over the 2 years preceding cessation of menses. In addition to the menopausal changes, serum concentrations of total cholesterol and LDL-cholesterol increased gradually in the pre-menopausal and post-menopausal years, but were significantly related to biological age only in the pre-menopausal groups (P < 0.05). Serum triglycerides and HDL-cholesterol levels remained virtually unchanged in the pre-menopausal as well as the post-menopausal groups and were only influenced by the actual menopause.

Serum lipids and lipoproteins are thus significantly altered as a consequence of the menopause. The result is a more atherogenic lipid profile which may partly explain the increased risk of cardiovascular disease observed in post-menopausal women.