Whole-body endurance exercise performance depends on maximal oxygen uptake (V˙O2max), exercise economy, and the ability to sustain a high percentage of the athlete’s maximum V˙O2 (3). Therefore, in sports such as running, cycling, and in particular exercise that involves both the arms and legs, e.g., cross-country skiing and rowing, V˙O2max is a strong predictor of performance in events lasting more than a few minutes (12,19). Thus, for rowing, V˙O2max may explain approximately 80% of the variance in 2000-m rowing ergometer performance within a group of trained subjects, and it also seems to be a good predictor of on-water performance (12).
In long-lasting endurance events, skeletal muscle oxidative capacity is also a strong predictor of performance (13) but close correlations between V˙O2max and performance are still observed in long-lasting ultraendurance running (18). Without neglecting peripheral factors, exercise economy, and technical and tactical skills, it is therefore obvious that endurance athletes and especially elite rowers must possess a high V˙O2max to compete at the highest international level.
V˙O2max relies on arterial oxygen delivery and, hence, maximal cardiac output (COmax) and arterial oxygen content (3,29). Because endurance training does not increase arterial hemoglobin concentration and because trained athletes typically experience mild-to-moderate exercise-induced arterial hypoxemia during maximal exercise (6), the superior aerobic capacity of elite trained subjects often relates to a very high COmax. This is substantiated by reports of high COmax in athletes, with individual values reaching above 40 L·min−1 (7). Such values seem to involve exceptional end-diastolic ventricular volumes and very high stroke volumes (SV), as observed in endurance-trained athletes (5). Whereas SV may increase with training, maximal hear rate (HRmax) does not. Rather, HRmax decreases by approximately 0.7 bpm·yr−1 with aging (31) and unless further increases of the ventricular SV compensate, COmax will decline. Accordingly, longitudinal and cross-sectional studies demonstrate that in men, V˙O2max peaks at an age between 20 and 25 yr and subsequently declines in line with the age-related decline in HRmax (1). Furthermore, it is well documented both among nonathletes and athletes that V˙O2max decreases gradually from approximately 20 to 80 yr of age (32). It has even been observed that endurance-trained men experience a more pronounced decline with aging than that in sedentary men (25). In addition to the loss of aerobic power, anaerobic power and capacity also decline with aging (28) and it seems that aging may have a greater effect on the anaerobic energy systems compared with that on the aerobic system (9).
Despite the inevitable decrease in HRmax and the common deterioration of physical exercise capacity, examples of elite endurance athletes who have been able to win world championship titles and Olympic medals at ages of approximately 40 yr exist. For example, the British rower Steven Redgrave won his last of five Olympic titles at an age of 38 and analogously, the Danish rower Eskild Ebbesen has been on the podium for five Olympic Games in a row, with the last medal won when he was 40 yr old. Also, in cross-country skiing and cycling, there have been some athletes capable of winning world titles or major competitions until their late 30s or beginning of the 40s. It is likely that some athletes may possess a unique talent that allows them to be competitive and beat younger opponents, although they are no longer at the physiological peak of their career, but it is also possible that these athletes do not experience the common age-related decline in aerobic and anaerobic power. Furthermore, the aging Olympic athlete may compensate for a loss in physical power by increased efficiency or improved technical and tactical skills. Longitudinal studies on elite cyclists (30) and a 5-yr case report on a world-class runner (14) indicate that improved efficiency is of major importance for further improvements in performance despite a lack of further increase in V˙O2max once a certain plateau has been reached. However, it remains unknown if efficiency may keep improving and how V˙O2max, efficiency, and the resulting exercise capacity are affected over a prolonged elite career. A recent case report on a former Tour de France winner (21) indicates that superior efficiency may be preserved with aging despite a normal age-induced decline in V˙O2max and that the age-related reduction in performance is explained by the decline in V˙O2max. The study of world-class athletes represents a unique population in which it can be investigated if the general physiological findings outlined above also hold true for this population.
To gain insights into the physiology of the aging elite athlete, we have collected physiological and performance data from a world-class lightweight rower across the age span 19–40 yr, representing the available test data from the beginning until the end of his elite career. The purpose of the study was to investigate if the continuous success is evident despite a reduced physiological capacity. The primary hypothesis was that a decline in V˙O2max would be compensated by increased ability to maintain a high percentage of V˙O2max for a prolonged period, which could possibly be related to improved efficiency.
The case athlete is a male world-class lightweight rower with six world championship titles, two indoor world championship titles, and five Olympic medals won during a career that has lasted approximately 20 yr. Physiological and performance data were collected from the age of 19 to 40 yr. His height was 1.84 m, competition weight was 72.5 kg (however, with a typical out-of-competition weight of between 76 and 78 kg), and body fat in 2012 was approximately 5%, as evaluated by dual-energy x-ray absorptiometry scanning (Lunar Madison DPX-IQ version 4.6.6; Lunar Corp., Madison, WI), with values between 5% and 8% when estimated from skinfold measures, corresponding to a lean body mass of approximately 70 kg. The use of historic physiological data and additional measurements of cardiac function were approved by the athlete and the ethics committee of the Capital Region of Denmark (H-4-2012-FSP).
Except for sabbatical breaks from elite rowing after the Olympics in 2004 and 2008, one, two or three tests of V˙O2max and HRmax have been performed every year, and data from the test that resulted in the highest V˙O2max are reported in the present article. Testing was always performed in the preparation period for a high-ranking competition and never in the off-season period. The peak oxygen uptake and HR values were determined as the highest V˙O2 value (15-s average) and HR obtained during 6-min maximal exercise on a rowing ergometer (Concept2, Morrisville, VT). These values are representative of the rower’s V˙O2max because peak oxygen uptake values during 6-min maximal test are reported to be similar to values obtained during incremental rowing protocols to exhaustion (12), and this has been verified in tests with the present subject. Oxygen uptake was continuously measured with online equipment (AMIS; Innovision, Odense, Denmark), and HR, with an HR monitor (Polar Electro, Finland). One minute and 3 min after the maximal test, a capillary blood sample was drawn from a finger and immediately transferred to a vial containing 25-IU heparin for lactate analysis using a YSI 2300 STAT Plus analyzer (YSI Inc., Yellow Springs, OH). Peak lactate level was determined as the higher of the two samples. Oxygen pulse was calculated as V˙O2max divided by the HRmax and expressed in milliliters of O2 per beat. Furthermore, a blood sample was obtained at rest before testing and hemoglobin concentration was measured on a Hemocue model Hb 201DM or Hb 201+ (Hemocue, Ängelholm, Sweden).
In addition to the maximal test, the subject also completed, in some years, submaximal tests consisting of 5-min bouts at five different intensities stepwise, increasing from approximately 220 to approximately 340 W, with HR and blood lactate measured. The only recurrent intensity from these tests is 300 W, and therefore, HR values from the last minute at 300 W are reported as an index of submaximal HR at a fixed workload. On two occasions (age 26 and 31), oxygen uptake and RER during exercise at 300 W were measured and the steady-state value is reported as the average V˙O2 and RER during the last minute of the 5-min exercise period. From these two tests, mechanical gross efficiency was calculated as the ratio of total work relative to expended energy, as estimated from the oxygen uptake and the corresponding RER (17).
In addition to the evaluation of physiological parameters, annual rowing performance tests with durations of 10 s, 60 s, 6 min, and 60 min were performed. Average power outputs from these tests are reported as indices of short-duration anaerobic power (10 s), anaerobic capacity (60 s), aerobic power (6 min), and endurance capacity (60 min). Average power values from the two best 2000-m rowing ergometer performances of 6 min 3.6 s obtained at the world indoor championships in 1998 and 6 min 3.8 s in 2004 are reported as background information and as reference values for the 6-min tests.
The general training concepts and weekly programs were fairly steady throughout the career, although there were some minor adjustments over the years and seasonal variations in the weekly training volume and intensity. Described in brief, the training consisted of approximately 15 h·wk−1 in total training volume, with the predominant part performed as specific rowing training on the water or during the winter on a rowing ergometer. In general, the training load, as indicated by training impulse scores (2), was fairly steady with an average of 1500 points per week, ranging from 2000 points during training camps to 800 points during tapering periods and competitions weeks (world cup regattas, world championships, and Olympic Games). On average, 15% of the 15 h or 135 min·wk−1 was conducted at intensities above 80% of peak aerobic power (corresponding to intensities above 300 W, as indicated by the HR), and the remaining 85% of the weekly training may be characterized as low- to moderate-intensity exercise (HR between 50% and 80% of the HRmax). The intense part of the training was both in season (spring and summer) and off season (during the winter) and included 3–4 weekly sessions, with intervals close to or above the power output eliciting V˙O2max. The less intense part of the training was conducted with a lower stroke frequency (lower cadence), but force generation was maintained in the strokes.
During the two sabbatical breaks from elite rowing (20 months from the age of 32 to 33 and 20 months again from age 37 to 38 yr), the subject did not participate in the regular training at the national rowing center but he remained physically active with daily endurance training consisting of 2–3 weekly rowing sessions per week and cycling or running on the remaining days. During the sabbatical breaks, the average training impulse score was approximately 1100 points per week, with approximately 400 of the points achieved in rowing-specific training.
Transthoracic echocardiography (Vivid E9; GE Healthcare, Horton, Norway) with a 2.5-MHz transducer was performed 2 wk after the last competition at the age of 40 yr. Resting in lateral supine position, the examination included two-dimensional recordings of parasternal, apical 2- and 4-chamber, and long axis views at the midventricular level. We measured end-diastolic right ventricular internal diameter, left ventricular diameter, interventricular septal diameter, and posterior wall diameter. Left ventricular volumes and ejection fraction (%) were obtained using the Simpson biplane method. Diastolic function was evaluated measuring peak transmitral inflow velocities (E and A), and peak diastolic velocities (E′) (cm·s−1), by pulsed wave tissue Doppler imaging.
Statistics and calculations
Simple linear regression was used to identify the relation between changes in HR and age. Otherwise, and in accordance with the nature of the case report, no statistical analyses were applied.
Aerobic capacity and HR
The first test of V˙O2max was performed at the age of 19 yr and elicited a peak value of 5.5 L·min−1 and HRmax of 182 bpm. During the following 5 yr, V˙O2max gradually increased to approximately 5.9 L·min−1, and with minor fluctuations, this level was maintained until the age of 31 (Fig. 1, top panel). After the 20-month sabbatical break from competitive rowing at the age of 32–33 yr, the return to elite rowing was associated with a V˙O2max value of 5.5 L·min−1, which subsequently increased to approximately 5.8 L·min−1 in the two following seasons leading up to the Olympic Games in 2008 at the age of 36. After the second sabbatical break from 37 to 38 yr of age, he was again tested at 39 yr old, with a V˙O2max value of 5.5 L·min−1, and subsequently, the V˙O2max again increased to 5.9 L·min−1 in the preseason leading up to the 2012 Olympics in London.
Whereas similar levels of V˙O2max were achieved until the last year of the career, HRmax has gradually declined from peak values between 180 and 184 bpm in the early 20s to peak values between 160 and 165 in the major parts of the test from the age of 31 to 40 yr (Fig. 1, middle panel), corresponding to an average decline of 0.9 bpm·yr−1 (regression line: HRmax = 196.5 − 0.9 × age; P < 0.01). In contrast, oxygen pulse increased, and at the age of 40, it reached a value of 35.5 mL O2 per beat (Fig. 1, bottom). Accordingly, the submaximal HR during exercise at 300 W continuously declined from approximately 155 bpm at the beginning of the career to a value below 135 bpm at the age of 40 (Fig. 2). V˙O2 at this exercise intensity was measured at the age of 25 yr as 4.57 L·min−1 and again at the age of 31 yr as 4.58 L·min−1. This implies that the gross efficiency at 300 W was 18.9% on both occasions, and the relative workload was approximately 78% of maximal aerobic power.
At the age of 40, heart structure analyses revealed a left ventricular mass of 198 g and a left ventricular end-diastolic diameter of 5.8 cm. Right ventricular diameter was 4.1 cm. Analyses of systolic function at rest demonstrated an SV of 100 mL and a 59% ejection fraction. Peak diastolic velocity (E′)—an evaluation of diastolic function—was 15.0 cm·s−1.
As illustrated by Fig. 3, both short-term performance (10-s and 60-s tests) and prolonged exercise capacity (6-min and 60-min tests) remained fairly stable during the career. The 10-s and 60-s tests were not performed every year, but it seems that the athlete was able to produce approximately 800 W on average in the 10-s test and almost 700 W in the 60-s test and the short-term performance did not decrease with age.
The 6-min test is the most commonly performed test because it resembles the exercise time in 2000-m rowing competitions, where the current world and Olympic records for the present rower’s boat type (LM4-) are held by crews including the case subject at 5 min 45 s and 5 min 47 s, respectively. During the first year of the elite career, average power in the 6-min test increased from 420 W at the age of 19 to 460 W at the age of 24, and this level has been repeated during testing at the ages of 36 and 40 yr. During indoor competitions (world championships in ergometer rowing), the subject’s best performances are 467 W on average during 2000 m (corresponding to a time of 6 min 3.6 s) at the age of 26 yr and 465 W (2000 m, time of 6 min 3.8 s) at the age of 32 yr. Peak blood lactate level after 6-min tests did not change during the career, with values of 21 mM achieved both at the age of 24 and 39 yr. Furthermore, the athlete’s lean body mass remained stable (range, 68–70 kg during out-of-competition assessments from 2001 to 2012) and his hemoglobin concentration was stable, with resting values between 145 and 150 g·L−1.
It is of major interest that V˙O2max remained absolutely unchanged despite a marked reduction in HRmax from the age of 19 to 40 yr and that this world-class athlete could maintain both anaerobic and aerobic power in tests ranging from 10 s to 1 h. Thus, it seems that the continued world-class performances of this athlete were related to maintenance of physiological capacities rather than compensatory improvements in technical or tactical skills.
Maximal oxygen uptake
The present observation of an unchanged V˙O2max in the pre-Olympic years clearly demonstrates that over this life-span, aging per se did not cause a reduction V˙O2max. This observation apparently contradicts the numerous reports of an age-induced reduction of V˙O2max of approximately 10% per decade in untrained healthy individuals (31). In addition, V˙O2max in endurance exercise-trained subjects has been reported to decline on the basis of cross-sectional studies (11) or longitudinal studies (15,16,34). Of special interest in relation to the present data is the finding that athletes with high baseline V˙O2max may experience an even more pronounced absolute V˙O2max deterioration with aging (8,25). The discrepancy between the apparent consensus of an age-induced deterioration of V˙O2max and the present results is likely because previously investigated subjects did not remain engaged in elite training that included high training volumes and both low- and high-intensity sessions whereas the present subject, as indicated by his training (HR) log, maintained his overall training stimulus and he did not experience increased difficulty in tolerating and maintaining this training load during the later stages of his career. The present observations lead to the suggestion that until the age of 40 yr, the common age-induced reduction of V˙O2max can be countered by very high amounts of intense endurance training—in this case performed on a continuous basis year after year for approximately 15 h·wk−1.
A reduction of HRmax has generally been viewed as the primary cause for the reduction of V˙O2max with age (10,11). In accordance with the established physiological phenomenon of an age-induced reduction of HRmax, the athlete in this case report demonstrated an age-related reduction in HRmax of approximately 0.9 bpm·yr−1. This is comparable with the reduction of approximately 0.8 bpm·yr−1 deduced from a meta-analysis of >;18,000 subjects (31). It is of interest to note that a recent investigation of octogenarian lifelong active athletes reported that several of the subjects had HRmax above 160 and a 91-yr-old former Olympic winner had an HRmax of 169 bpm, which is higher than the value obtained by the present case subject in last year’s maximal tests (33). Nevertheless, the current case report supports the well-established physiological phenomenon of an age-induced reduction of HRmax despite engagement in intense training. Importantly and surprisingly, the age-induced reduction in HRmax was not associated with a reduction in V˙O2max in the present case report. This may be because COmax can be reached at nonmaximal HR (20).
Oxygen pulse, an indirect indicator of SV, is typically approximately 25 mL per beat in young endurance athletes (34) and has been observed to decline with age to approximately 18 mL per beat in 70-yr-old master athletes (26). In contrast, oxygen pulse increased with age in the current case study (Fig. 1). According to Fick’s principle, this observation demonstrates that either the peak SV has increased over time or the arteriovenous oxygen difference of the active muscle must have been expanded. Because the subject’s hemoglobin concentration remained unchanged over the years, it seems that arterial oxygen carrying capacity did not change, and it is most likely that an increased SV is the primary compensatory mechanism (5). Furthermore, in rowing, exercise-induced arterial hypoxemia is commonly reported in trained subjects (23), and it could be hypothesized that the aging-induced reduction of COmax and, thus, increased lung capillary mean transit time may outweigh arterial hypoxemia and explain the maintained V˙O2max. However, it seems that exercise-induced hypoxemia is potentiated with aging (27), which makes this hypothesis unlikely.
At the age of 40, the case athlete underwent an examination of cardiac function to investigate if an unusually large heart could be an explanation for the maintained V˙O2max. Compared with normal values, the observed left ventricular end-diastolic diameter of 5.8 cm is above the upper limit of 5.5 cm but the left ventricular mass of 198 g is comparable with an age-matched mean of 196 g (4). Eccentric hypertrophy was evident in the case athlete, but no abnormal adaptations in left interventricular septal or posterior wall thickness were observed. This contrasts with the relatively high incidence of combined eccentric and concentric hypertrophy reported in elite rowers (24). Also, the resting SV of 100 mL is within the normal athletic range, and the case subject presented a normal diastolic function (E′) comparable to the normal population at the age of 40 yr (22). In summary, the left ventricular end-diastolic diameter observed for the case athlete was above the limits for normal subjects but the cardiac structure and function were not extreme compared with those in other endurance-trained elite athletes (5). Because echocardiography was not part of the annual testing but performed only at the age of 40, it is not possible to infer if the high values observed are mainly related to genetic predisposition or the athletic training history. However, the continuous increase of the subject’s oxygen pulse indicates that training adaptations are involved.
The present data indicate that the rower’s efficiency remained stable, as the oxygen uptake at 300 W was similar at ages 25 and 31. Moreover, both the maximal 6-min and 60-min performances were constant during the investigated period when seasonal fluctuations are neglected (Fig. 3). If efficiency had been increased, we would have expected a gradual performance improvement, as the V˙O2max was constant. Exercise efficiency has been reported to increase over a 5-yr period in world-class cyclists (30) and a long-distance runner (14). It is possible that differences exist between rowing and the previous reported observations from cycling and running, but it is also likely that the rower at the age of 25 already experienced the improvement in efficiency that is expected in the developing phase of an elite career.
Prolonged exercise performance
From the age of approximately 25 until 40 yr, the maintained exercise capacity in 60-min tests demonstrates that not only was V˙O2max preserved for almost two decades but the ability to work at a high percentage of V˙O2max was also preserved. It therefore seems likely that peripheral training adaptations such as increased capillary density and elevated mitochondrial capacity were developed during the first years of the elite career, parallel with the improvements in 6-min and 60-min test performances. The subsequent plateau in power output during the prolonged tests indicates a plateau in these parameters because any change in the ability to work at a high percentage of V˙O2max would be expected to affect prolonged exercise performance (3). Furthermore, it should be noted that the power output values obtained during the 6-min tests are very close to the athlete’s personal best of 6 min 3.6 s for 2000 m, demonstrating that the reported test data are representative of the athlete’s true maximum. With regard to the athlete’s performance level, it is worth mentioning that the average 2000-m ergometer performance for the team remained fairly constant over the years despite changing crew members in the coxless four (data not shown). This indicates that the continued high racing performance of this particular athlete was not due to a compensatory increase of physical capacity of the rest of the team. A further concern in elite sport is the potential influence of performance-enhancing drugs. The constant performance level through a 20-yr career indicates that no periods of abuse have existed, and this is further substantiated by the constant hemoglobin concentrations and the fact that the athlete has never had a case with antidoping authorities despite intensive in- and out-of-competition testing.
Anaerobic power and capacity
Data from cross-sectional studies indicate that anaerobic exercise capacity evaluated as performance in 10-s and 30-s cycling tests will decline by approximately 8% per decade (9), and although the reduction is most prominent at ages above 40 yr (28), it seems that aging has similar or maybe an even greater effect on anaerobic power compared with that on aerobic power in trained masters athletes (9). However, in the current case, there are no indications of reduced anaerobic work capacity, as evaluated from the 10-s and 60-s tests (Fig. 3). Thus, it seems that although the average population and the average endurance-trained master athlete experience significant declines in both aerobic and anaerobic exercise capacities, individual athletes may preserve both anaerobic and aerobic power until the age of 40 when engaged in intensive exercise training.
In summary, the present case is the first to follow an elite athlete with annual testing for more than 20 yr and it is demonstrated that despite aging and a significant decline in HRmax, aerobic and anaerobic power as well as performance may be maintained in highly trained subjects. Notably, the marked increase in the athlete’s oxygen pulse was associated with a large left ventricular end-diastolic diameter, but the cardiac structure and function were not extreme compared with those in other endurance-trained elite athletes.
This case report on an aging world-class athlete demonstrates that over a 20-yr career, it is possible to maintain physiological capacities that allow success at the highest international level. The longitudinal study furthermore indicates that until the age of 40 yr, V˙O2max may be maintained because a steady increase in the oxygen pulse may fully compensate for the significant decline in the maximal heart frequency.
Eskild Ebbesen and Team Danmark are acknowledged for sharing otherwise inaccessible historic data. No funding was obtained for the present study.
The authors declare no conflict of interest.
The results of the present study do not constitute endorsement by the American College of Sports Medicine.
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