Changes in cardiorespiratory function in different groups of former and still active male cross-country skiers: a 28-30-year follow-up study

Rationale and design of the Birkebeiner Ageing Study - a prospective cohort study of older endurance athletes

BACKGROUND

While regular physical activity is associated with reduced mortality and morbidity in general populations, health outcomes and functional capacity related to upholding strenuous endurance exercise beyond the age of 65 years are only sparsely studied. The aim of this study is to assess associations of prolonged strenuous endurance sport practice with ageing, functional decline, morbidity and longevity among older recreational endurance athletes, during long-term follow-up.

METHODS

Prospective cohort study of older recreational endurance athletes in Norway. All skiers aged 65 years and older who participated in a long-distance endurance competition, the annual 54-km Birkebeiner cross-country ski race in 2009 or 2010, were invited. The participants answered an extensive baseline questionnaire about lifestyle habits, including leisure-time physical activity and endurance sport participation, diseases, medication use and physical and mental health, with follow-up questionnaires planned every fifth year until 2029. New participants may be invited with the aim to increase the study size. Endpoints such as all-cause and disease-specific mortality, incidence and cumulative prevalence of diseases, use of medication, physical and mental health and functional decline will be assessed subsequently. Out of 658 invited skiers (51 women), 551(84%) completed the baseline questionnaire and were included in the study. The mean age was 68.8 years (median 68, range 65- 90). At baseline, the participants had completed the Birkebeiner race for an average of 16.6 years and reported an average of 33.4 years of regular endurance exercise, with one out of five reporting at least 50 years of exercise. In all, 479 (90%) reported that they were still practicing leisure-time physical activity of moderate or vigorous intensity at least twice weekly. The prevalence of cardiovascular risk factors and diseases was low.

DISCUSSION

This prospective study of a cohort of recreational athletes exposed to prolonged and strenuous endurance exercise, could complement population-based studies by providing data on associations between life-long endurance sport participation, aging, functional decline and health outcomes during long-term follow-up.

The Impact of Training on the Loss of Cardiorespiratory Fitness in Aging Masters Endurance Athletes

Elite masters endurance athletes are considered models of optimal healthy aging due to the maintenance of high cardiorespiratory fitness (CRF) until old age. Whereas a drop in VO₂max in masters athletes has been broadly investigated, the modifying impact of training still remains a matter of debate. Longitudinal observations in masters endurance athletes demonstrated VO₂max declines between -5% and -46% per decade that were closely related to changes in training volume. Here, using regression analyses, we show that 54% and 39% of the variance in observed VO₂max decline in male and female athletes, respectively is explained by changes in training volume. An almost linear VO₂max decrease was observed in studies on young and older athletes, as well as non-athletes, starting a few days after training cessation, with a decline of as much as -20% after 12 weeks. Besides a decline in stroke volume and cardiac output, training cessation was accompanied by considerable reductions in citrate synthase and succinate dehydrogenase activity (reduction in mitochondrial content and oxidative capacity). This reduction could largely be rescued within similar time periods of training (re)uptake. It is evident that training reduction or cessation leads to a considerably accelerated VO₂max drop, as compared to the gradual aging-related VO₂max decline, which can rapidly nullify many of the benefits of preceding long-term training efforts.

The Effects of a Physically Active Lifestyle on the Health of Former Professional Football Players

The purpose of this investigation was to determine if a physically active lifestyle affects the health of former football players. Sixty former professional football players aged 40⁻50 years and who ended their sports career at least ten years ago were recruited for the study and grouped into two groups based on their physical activity habits after their retirement. Health and lifestyle characteristics were collected through a questionnaire to obtain information about recreational physical activity levels, diseases, family medical history, smoking, alcohol intake and dietary habits. Furthermore, lung functions, blood parameters and cardiovascular health were evaluated. Our results showed that body weight and body fat percentage were significantly higher in retired footballers who had a sedentary lifestyle compared to those who were physically active. The absolute and predicted values for forced expiratory volume in one-second values were higher in the active group. Twelve retired athletes were found to have intraventricular conduction delay. The findings suggest that former footballers who have higher levels of physical activity have advanced body composition, respiratory functions and serum lipids compared to former footballers with less active lifestyles. It is recommended that former elite athletes should maintain physically active lifestyles to sustain their health and reduce the risk of disease and disability in the later years of life.

Effects of Two Years of Calorie Restriction on Aerobic Capacity and Muscle Strength

PURPOSE

Calorie restriction (CR) improves health span and delays age-related diseases in many species. The multicenter Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) study was the first randomized controlled trial of CR in nonobese humans. The aim of this investigation was to determine the effects of CR on V˙O2max and muscle strength in the CALERIE trial.

METHODS

Healthy, normal-weight, and mildly overweight women and men (n = 218, mean ± SE age = 37.9 ± 0.5 yr) were randomized to 25% CR or an ad libitum (AL) control condition in a 2:1 allocation (143 CR, 75 AL). V˙O2max was determined with an incremental treadmill test; the strength of the knee flexors and extensors was assessed by dynamometry at baseline, 1 yr, and 2 yr.

RESULTS

The CR group achieved an average 11.9% ± 0.7% CR during the 2-yr intervention. Body weight decreased in CR (-7.7 ± 0.4 kg), but not AL (+0.2 ± 0.5 kg). Absolute V˙O2max (L·min) decreased at 1 and 2 yr with CR, whereas V˙O2max expressed relative to body mass increased at both time points (1 yr: +2.2 ± 0.4; 2 yr: +1.9 ± 0.5 mL·kg·min) and relative to AL. The CR group increased their treadmill test time and workload at 1 and 2 yr. Strength results in CR were similar, with decreases in absolute flexor and extensor strength, but increases when expressed relative to body mass. No changes were observed for V˙O2max expressed relative to lean body mass or leg lean mass.

CONCLUSIONS

Two years of modest CR without a structured exercise component did not appear to compromise aerobic capacity in healthy nonobese adults. The clinical implications of the observed changes in V˙O2max and muscle strength will be important to explore in future studies.

Maximal oxygen consumption in healthy humans: theories and facts

This article reviews the concept of maximal oxygen consumption ([Formula: see text]) from the perspective of multifactorial models of [Formula: see text] limitation. First, I discuss procedural aspects of [Formula: see text] measurement: the implications of ramp protocols are analysed within the theoretical work of Morton. Then I analyse the descriptive physiology of [Formula: see text], evidencing the path that led to the view of monofactorial cardiovascular or muscular [Formula: see text] limitation. Multifactorial models, generated by the theoretical work of di Prampero and Wagner around the oxygen conductance equation, represented a radical change of perspective. These models are presented in detail and criticized with respect to the ensuing experimental work. A synthesis between them is proposed, demonstrating how much these models coincide and converge on the same conclusions. Finally, I discuss the cases of hypoxia and bed rest, the former as an example of the pervasive effects of the shape of the oxygen equilibrium curve, the latter as a neat example of adaptive changes concerning the entire respiratory system. The conclusion is that the concept of cardiovascular [Formula: see text] limitation is reinforced by multifactorial models, since cardiovascular oxygen transport provides most of the [Formula: see text] limitation, at least in normoxia. However, the same models show that the role of peripheral resistances is significant and cannot be neglected. The role of peripheral factors is greater the smaller is the active muscle mass. In hypoxia, the intervention of lung resistances as limiting factors restricts the role played by cardiovascular and peripheral factors.

Exercise-training-induced changes in metabolic capacity with age: the role of central cardiovascular plasticity

Although aging is typically associated with a decline in maximal oxygen consumption (VO2max), young and old subjects, of similar initial muscle metabolic capacity, increased quadriceps VO2max equally when this small muscle mass was trained in isolation. As it is unclear if this preserved exercise-induced plasticity with age is still evident with centrally challenging whole body exercise, we assessed maximal exercise responses in 13 young (24 ± 2 years) and 13 old (60 ± 3 years) males, matched for cycling VO2max (3.82 ± 0.66 and 3.69 ± 0.30 L min(-1), respectively), both before and after 8 weeks of high aerobic intensity cycle exercise training. As a consequence of the training both young and old significantly improved VO2max (13 ± 6 vs. 6 ± 7 %) and maximal power output (20 ± 6 vs. 10 ± 6 %, respectively) from baseline, however, the young exhibited a significantly larger increase than the old. Similarly, independently assessed maximal cardiac output (Q max) tended to increase more in the young (16 ± 14 %) than in the old (11 ± 12 %), with no change in a-vO2 difference in either group. Further examination of the components of Q max provided additional evidence of reduced exercise-induced plasticity in both maximal heart rate (young -3 %, old 0 %) and stroke volume (young 19 ± 15, old 11 ± 11 %) in the old. In combination, these findings imply that limited central cardiovascular plasticity may be responsible, at least in part, for the attenuated response to whole body exercise training with increasing age.