Exercise and Aging: 

The number of individuals over 50 who engage in regular exercise or competitive sports has seen a significant increase in recent decades. This trend is expected to continue as the global elderly population is projected to rise from 6.9% in 2000 to an estimated 19.3% by 2050. Within this growing demographic, many older adults participate in physical activities for enjoyment, recreation, and fitness, while others approach their training with the same dedication and intensity as Olympic athletes. These older athletes, often referred to as masters or senior athletes, participate in a wide range of activities, from marathon running to powerlifting, and have achieved remarkable success and set impressive performance records.

Despite their advanced age, highly trained older athletes often exhibit strength and endurance levels that surpass those of untrained individuals in their age group. However, even these elite older athletes experience a decline in performance as they enter their fourth or fifth decade of life.

Changing Physical Activity Patterns with Age:

In modern societies, voluntary physical activity tends to decline after individuals reach physical maturity. Advancements in technology have reduced the physical demands of daily life. This trend of decreasing physical activity with age is not only observed in humans but also in laboratory animals. For instance, studies on rats have shown that their voluntary running distance significantly decreases in their later months of life compared to their early months.

Given these natural patterns of decreasing physical activity with age, it becomes essential to understand why some older individuals choose to remain physically active, particularly through competitive sports or exhaustive training.

Motivations for Older Athletes:

The psychological factors that motivate older athletes to participate in competitive sports or maintain rigorous training regimens are not precisely defined. However, their goals are believed to align with those of younger athletes. These motivations might include a desire for personal achievement, maintaining physical fitness, pursuing a passion, and seeking the social aspects and camaraderie that come with participation in sports.

Distinguishing Aging Effects from Reduced Activity:

It can be challenging to distinguish between the effects of aging itself (referred to as primary aging) and those resulting from reduced physical activity and comorbidities that often accompany aging. Researchers studying aging typically employ cross-sectional designs, which have certain limitations compared to longitudinal studies. These limitations include factors like historical changes in healthcare, diet, exercise habits, and lifestyle variables that can impact age cohorts differently. Additionally, selective mortality, where the study population consists of surviving members of a cohort that has experienced some degree of mortality, can skew results. Finally, when exercise studies exclude individuals with underlying diseases or medication use, it becomes difficult to generalize findings to the larger aging population.

Understanding the impact of primary aging alone on physiological function is essential, but the interpretation and applicability of research findings can vary depending on study design and the specific population being studied.

Changes in Height, Weight, and Body Composition with Aging:

As individuals age, several changes in height, weight, and body composition occur:

1. Reduction in Height: The process of losing height typically begins around the ages of 35 to 40 and is primarily attributed to the compression of intervertebral disks and poor posture. Later, around 40 to 50 years for women and 50 to 60 years for men, conditions like osteopenia and osteoporosis can contribute to height reduction. Osteopenia is a condition characterized by a reduction in bone mineral density below normal levels, while osteoporosis involves severe bone mass loss and microarchitecture deterioration, leading to a higher risk of fractures.
2. Weight Gain and Loss: Weight gain typically occurs between ages 25 and 45 due to a combination of decreased physical activity and excess caloric intake. Beyond the age of 45, weight tends to stabilize for approximately 10 to 15 years before decreasing as the body loses bone calcium and muscle mass. Many individuals over 65 to 70 years old may lose their appetite, leading to insufficient calorie intake, which results in weight loss. However, an active lifestyle can stimulate appetite and help maintain calorie intake, thus preventing frailty in old age.
3. Gain in Body Fat: Starting around the age of 20, there is a trend toward an increase in body fat as people age. This increase is primarily driven by factors such as diet, physical inactivity, and reduced ability to mobilize fat stores. However, physically active older individuals, including athletes, tend to have significantly lower body fat percentages compared to sedentary individuals of the same age. Additionally, aging leads to a shift in fat storage from the periphery to the central region of the body, which is associated with cardiovascular and metabolic diseases.
4. Decrease in Fat-Free Mass: Fat-free mass, which includes muscle and bone mass, progressively decreases in both men and women, beginning around the age of 40. The most significant decline occurs in muscle mass, making up about 50% of fat-free mass. The term “sarcopenia” is used to describe this age-related loss of muscle mass. Although reduced physical activity plays a major role in this decline, other factors contribute to muscle mass loss. There is ongoing research on the mechanisms behind this decline, with evidence suggesting reduced muscle protein synthesis and increased muscle protein breakdown with age.
5. Decrease in Bone Mineral Content: Bone mineral content begins to decrease around age 30 to 35 in women and age 45 to 50 in men. This decline is due to an imbalance between bone formation and resorption, with resorption outpacing formation. Physical inactivity, especially the absence of weight-bearing exercise, is a significant contributor to bone loss.

Impact of Physical Activity on Aging and Body Composition:

• Physically active older individuals, including athletes, tend to have lower body fat percentages and are less likely to experience the shift in fat storage toward the central body region.
• Muscle and bone mass loss with aging can be attributed to decreased physical activity, particularly a lack of weight-bearing exercise.
• Resistance training is more effective at increasing fat-free mass, including muscle, than aerobic training, both in younger and older individuals.
• Older men and women who engage in exercise can reduce weight, body fat percentage, and fat mass while increasing fat-free mass.
• Moderate caloric intake reduction (500-1,000 kcal/day) combined with exercise is generally recommended for achieving favorable changes in body composition, particularly a reduction in body fat.

Physiological Responses to Acute Exercise and Age-Related Changes:

As individuals age, several physiological changes occur, affecting muscular and cardiovascular endurance, as well as muscular strength. These changes are influenced by physical activity levels and genetics. Reduced physical activity, which tends to be a natural phenomenon during the aging process in both animals and humans, exacerbates these physiological declines.

Strength and Neuromuscular Function:

• While the strength needed to meet the demands of daily living remains constant throughout life, maximal strength, typically well above daily requirements during early adulthood, steadily decreases with age.
• Age-related strength decline may reach a point where simple activities become challenging, such as standing up from a sitting position in a chair.
• Activities requiring strength, like opening a jar with resistance, can become increasingly difficult, especially after the age of 60.
• Resistance exercises targeting specific muscle groups can help older individuals maintain and even improve strength, allowing them to perform better than sedentary individuals much younger than themselves.
• Strength losses with aging are modality-specific, with greater losses in isokinetic strength at high angular velocities and greater losses in concentric strength compared to eccentric strength.
• The substantial loss of muscle mass that accompanies aging or reduced physical activity contributes significantly to age-related reductions in muscle strength.
• Muscle cross-sectional area and muscle strength show a strong correlation, emphasizing the importance of preserving muscle mass with aging.

Muscle Fiber Type and Loss:

• Changes in muscle fiber type with aging are complex and influenced by factors such as activity levels.
• Cross-sectional studies have suggested that muscle fiber type (type I vs. type II) remains stable throughout life.
• Longitudinal studies indicate that activity levels may play a role in fiber type distribution. Decreased activity or inactivity may lead to a greater proportion of type I fibers.
• Some elite athletes who decreased their activity levels showed a significantly greater proportion of type I fibers compared to when they were younger, while those who remained highly trained had no change.
• The increase in type I fibers may be due to a decrease in the number of type II fibers, resulting in a greater relative proportion of type I fibers.
• The decline in muscle strength with aging can be attributed to both a decrease in the number and size of muscle fibers.
• Some studies have reported a loss of approximately 10% of total muscle fibers per decade after age 50.
• The size of both type I and type II muscle fibers decreases with aging.

Impact of Exercise on Age-Related Changes:

• Endurance training (e.g., distance running) has limited impact on mitigating the decline in muscle mass with aging.
• Strength training, in contrast, plays a crucial role in reducing muscle atrophy in aging adults and may even lead to an increase in muscle cross-sectional area.
• Preserving muscle mass and strength through resistance exercises is essential for maintaining functional abilities and quality of life as one ages.

Aging leads to reductions in muscular and cardiovascular endurance, as well as muscular strength. While maintaining maximal strength becomes challenging with age, resistance exercises can help older individuals combat muscle atrophy and maintain functional abilities. Muscle fiber type changes are complex and may be influenced by activity levels. Resistance training is particularly effective in preserving muscle mass and strength in older adults, contributing to a better quality of life in later years.

Aging and Neuromuscular Changes:

Aging is accompanied by significant changes in the nervous system’s ability to process information and activate muscles, impacting various aspects of motor function. Here are some key points about how aging affects neuromuscular function:

1. Information Processing and Movement: Aging influences the ability to detect stimuli and process information required to initiate a motor response. This includes both simple and complex movements. Overall, aging tends to slow down motor responses. However, physically active older individuals exhibit only slight declines in motor speed compared to younger active individuals.
2. Motor Unit Activation: Motor unit activation, which involves the recruitment of motor neurons and muscle fibers, tends to be reduced in older adults. For example, studies have shown that older men, around 80 years old, have lower firing rates and longer twitch contraction durations compared to younger men, around 20 years old. However, some research suggests that older individuals can still maximally recruit skeletal muscle, indicating that reduced strength is primarily due to local muscle factors rather than neural factors.
3. Impact of Exercise: Engaging in regular physical activity, including exercise and sports, can mitigate the effects of aging on neuromuscular performance. While physical activity may not halt the biological aging process, it can significantly reduce many of the declines in physical work capacity associated with aging.
4. Muscle Quality: Despite the loss of muscle mass in active aging individuals, the structural and biochemical properties of the remaining muscle mass are well-maintained. For example, in older endurance runners, the number of capillaries per unit area in muscle tissue remains similar to that of young runners. Additionally, oxidative enzyme activities in the muscles of endurance-trained older athletes are only slightly lower (10% to 15%) than those of endurance-trained young athletes.
5. Adaptability to Endurance Training: Skeletal muscle’s adaptability to endurance training appears to be minimally affected by aging. Older runners who engage in endurance training maintain a high oxidative capacity in their muscles, with only slight differences compared to young elite runners. This suggests that the aging process has limited impact on the muscle’s ability to adapt to endurance training.

Cardiovascular and Respiratory Function with Aging:

Aging has a substantial impact on both cardiovascular and respiratory functions. These changes can significantly influence an individual’s endurance performance.

Cardiovascular Function:

As people age, several notable changes occur in their cardiovascular function:

1. Maximal Heart Rate (HRmax): Aging leads to a reduction in HRmax. While children typically have HRmax values ranging from 195 to 215 beats per minute (bpm), the average 60-year-old has an HRmax of around 166 bpm. HRmax decreases at a rate of approximately 1 bpm per year.
2. Improved HRmax Estimation: A more accurate formula for estimating HRmax is proposed as HRmax = [208 – (0.7 × age)]. This formula provides a more precise estimate compared to the traditional HRmax = 220 – age, which often overestimates or underestimates HRmax.
3. Reduction in HRmax with Aging: This reduction is consistent among both sedentary and well-trained adults. Even typically active older individuals experience a decline in HRmax.
4. Causes of Reduced HRmax: Potential causes include changes in the cardiac conduction system, particularly in the SA node and the bundle of His, as well as downregulation of b1 adrenergic receptors in the heart, which decreases sensitivity to catecholamine stimulation.
5. Maximal Stroke Volume (SVmax): Highly trained older adults experience a modest reduction of around 10-20% in SVmax. This is associated with decreased responses to catecholamine stimulation, myocardial contractility, and changes in the heart’s Frank-Starling mechanism.
6. Exercise Training Benefits: Early-life exercise training can help mitigate the decline in SVmax. However, the effectiveness of this intervention decreases when training is initiated later in life.
7. Primary Cause of Reduced Cardiac Output: In highly trained individuals, the decrease in maximal cardiac output with aging is primarily due to a reduced heart rate, with a lesser contribution from a decrease in stroke volume. This reduction in cardiac output plays a key role in reduced V̇O2max (maximal oxygen consumption) observed in older athletes.
8. Maximal Oxygen Consumption (V̇O2max): Older athletes exhibit reduced V̇O2max primarily due to a decreased maximal heart rate, despite heart volumes being similar to those of younger athletes.
9. Peripheral Blood Flow: Aging leads to reduced peripheral blood flow, particularly to the legs. This is despite capillary density in the muscles remaining unchanged. Several factors, including blunted functional sympatholysis and reduced local vasodilators, contribute to this reduced blood flow.
10. Compensation Mechanism: Older athletes compensate for reduced blood flow to the legs during submaximal exercise by extracting more oxygen from the blood, resulting in similar oxygen uptake at a given submaximal work intensity.
11. Aging vs. Deconditioning: Distinguishing between changes in cardiovascular function due to aging alone and those due to cardiovascular deconditioning resulting from inactivity or reduced training intensity is challenging. Both factors play a role, but the exact contribution of each remains unclear. Nevertheless, even older athletes generally train at lower volumes and intensities compared to their younger counterparts.

Respiratory Function:

While not explicitly discussed in this text, aging also affects respiratory function. Changes in lung elasticity, chest wall compliance, and respiratory muscle strength can lead to decreased lung function, reduced exercise capacity, and increased susceptibility to respiratory conditions. Engaging in a healthy lifestyle and regular physical activity can help mitigate some of these age-related changes in respiratory function.

Respiratory Function and Aging:

As individuals age, respiratory function undergoes significant changes, particularly in sedentary individuals. These changes can affect lung capacity and ventilation during exercise.

1. Lung Function Changes: Vital capacity (VC) and forced expiratory volume in 1 second (FEV1.0) decrease linearly with age, typically starting around age 20 to 30. Conversely, residual volume (RV) tends to increase, while total lung capacity (TLC) remains relatively unchanged. Consequently, the ratio of residual volume to total lung capacity (RV/TLC) increases, indicating that less air can be efficiently exchanged in the lungs. For example, in our early 20s, RV accounts for 18% to 22% of TLC, but this can rise to 30% or more by age 50. Smoking can accelerate this increase in RV/TLC.
2. Maximal Ventilatory Capacity: Maximal expiratory ventilation (V̇Emax) typically increases during growth and physical maturity and then decreases with age. For instance, V̇Emax values may range from about 40 L/min for 4- to 6-year-old boys to 70-90 L/min for 60- to 70-year-old men. Similar patterns are observed in girls and women, but their absolute values are generally lower due to smaller body size. The relationship between total lung capacity and height influences these gender and age-related differences.
3. Factors Contributing to Changes: Several factors contribute to the changes in pulmonary function observed with age. The most significant factor is the loss of elasticity in lung tissue and the chest wall. This loss of elasticity increases the effort required for breathing and stiffens the chest wall, which is responsible for most of the observed reduction in lung function. Despite these changes, the lungs maintain a remarkable reserve and continue to support maximal exertion, with no apparent limitations on exercise capacity.
4. Impact on Endurance Athletes: Endurance-trained older athletes experience only slight decreases in pulmonary ventilation capacities. More importantly, the decreased aerobic capacity observed in older athletes cannot be attributed to changes in pulmonary ventilation. During strenuous exercise, both normally active older individuals and athletes can maintain near-maximal arterial oxygen saturation. Therefore, changes in lung function or the blood’s oxygen-carrying capacity do not appear to be responsible for the observed decline in V̇O2max (maximal oxygen consumption) reported in aging athletes. Instead, the primary limitation seems to be related to oxygen transport to the muscles, particularly due to cardiovascular changes that affect maximal heart rate, maximal cardiac output, and blood flow to the exercising muscles. The preservation of O2 extraction with age suggests that the capacity for oxygen utilization by the muscles remains intact in older exercisers.

Aerobic and Anaerobic Function in Aging:

When examining the effects of aging on aerobic and anaerobic functions during exercise, two crucial variables come into focus: V̇O2max (maximal oxygen consumption) and lactate threshold.

V̇O2max:

To understand how V̇O2max changes with age, several important considerations must be taken into account. Firstly, one must decide whether to express V̇O2max values in liters per minute (L/min) or per kilogram of body weight (ml · kg–1 · min–1) to account for body size differences. The choice depends on the type of exercise, with non-weight-bearing exercises like cycling more suited to liters per minute and weight-bearing activities like running requiring values per unit of body weight.

Secondly, the method of expressing change values with aging matters. Changes can be expressed as an absolute change (in L/min or ml · kg–1 · min–1) or as a percentage change, where the percentage change = [(final value – initial value) / initial value] × 100. This choice can have significant implications. For example, a 30-year-old man with an initial V̇O2max of 50 ml · kg–1 · min–1, decreasing to 40 ml · kg–1 · min–1 at age 50, shows a decline of 10 ml · kg–1 · min–1 over 20 years, equivalent to a 20% decrease (10/50). However, when expressed in ml · kg–1 · min–1, the younger man has experienced a 20% decrease, whereas the older man has seen a 29% decrease, illustrating a substantial difference when expressed as a percentage change.

Many studies report both the absolute (ml · kg–1 · min–1) and relative (%) decrease. Now, let’s explore the changes in V̇O2max with aging, focusing first on normally active individuals.

Normally Active People: The initial studies on aging and physical fitness, conducted in the late 1930s by Sid Robinson, demonstrated that V̇O2max in normally active men consistently declines from age 25 to age 75. On average, aerobic capacity decreases at a rate of 0.44 ml · kg–1 · min–1 per year, which is approximately 1% per year or 10% per decade. Women between the ages of 25 and 60 also experience a decline close to 1% per year.

A review of 11 cross-sectional studies on men, mostly under age 70, showed an average decrease rate of 0.41 ml · kg–1 · min–1 per year. In the same review, an analysis of six cross-sectional studies on women resulted in an average decline rate of 0.30 ml · kg–1 · min–1 per year. This review did not report the average decline as a percentage of the subjects’ initial V̇O2max values.

In the mid-1990s, a large cross-sectional study involving 1,499 men and 409 women, all healthy individuals who underwent a maximal treadmill test with direct V̇O2 measurement, reported a decline of 0.46 ml · kg–1 · min–1 per year in men (equivalent to 1.2% per year) and 0.54 ml · kg–1 · min–1 per year in women (equivalent to 1.7% per year).

Few longitudinal studies have been conducted in this area, and the limited available data show variations in the rate of decline in aerobic capacity. These variations can be attributed to differences in subjects’ activity levels and ages at the beginning of the studies. Nevertheless, a commonly agreed-upon estimate for the rate of decline in V̇O2max is approximately 10% per decade or 1% per year (equivalent to –0.4 ml · kg–1 · min–1 per year) in relatively sedentary men. Similar trends are observed in women, although fewer subjects have been studied.

Older Athletes and the Effect of Aging on Endurance:

A comprehensive study conducted by D.B. Dill and his colleagues from the Harvard Fatigue Laboratory, focusing on distance runners and aging, provides valuable insights into the impact of aging on endurance performance.

Don Lash and the Harvard Study:

• The study included Don Lash, a world-record holder for the 2-mile run in 1936. Lash was still running about 45 minutes per day at age 49.
• Despite Lash’s continued activity, his V̇O2max had decreased from 81.4 ml · kg–1 · min–1 at age 24 to 54.4 ml · kg–1 · min–1 at age 49, representing a 33% decline.
• Runners who did not continue training during middle age experienced even larger declines, with aerobic capacities decreasing by about 43% from age 23 to age 50 (from 70 to 40 ml · kg–1 · min–1).
• These findings indicate that prior training offers limited advantages for endurance capacity in later life unless individuals remain engaged in vigorous activity.
• However, individuals with high initial values have a significant functional reserve, and this substantial decrease in aerobic capacity has minimal impact on their ability to perform daily activities.

Longitudinal Studies:

• More recent longitudinal studies on older male runners and rowers have demonstrated declines in aerobic capacity and cardiovascular function as well as changes in muscle fiber composition with aging.
• Athletes who continued high-volume and high-intensity training experienced a 5% to 6% decline in V̇O2max per decade.
• On the other hand, elite runners who stopped training experienced a nearly 15% decline in aerobic capacity per decade (equivalent to 1.5% per year), resulting from both deconditioning and aging.

Studies on Women:

• Fewer studies have been published on women, but they show similar trends. Cross-sectional and longitudinal data reveal a rate of decline in V̇O2max of approximately 0.47 ml · kg–1 · min–1 per year in men (0.8% per year) and 0.44 ml · kg–1 · min–1 per year in women (0.9% per year).

Effect of Intense Training:

• A 25-year follow-up study examined highly competitive older male distance runners who maintained a similar relative intensity of training as when they were younger.
• Their V̇O2max values (in L/min) decreased only 3.6% over the 25-year period. Although their maximal oxygen uptake decreased slightly, most of this change was due to an increase in body weight.
• These findings suggest that intense training can slow the rate of decline in aerobic capacity during the early and middle years of adulthood (e.g., 30-50 years), but its impact diminishes after the age of 50.

Factors Influencing Decline in V̇O2max:

• Various factors influence the rate of decline in V̇O2max, including genetics, general activity level, training intensity, training volume, changes in body weight and composition, and age range.
• There is no universal consensus on which factors are the most significant contributors to the decline.

Lactate Threshold and Its Changes with Aging:

The lactate threshold (LT), a crucial physiological marker in young endurance-trained adults, is associated with exercise performance in various distance events, from 2 miles to the marathon. However, there is limited research addressing the changes in lactate threshold, specifically LT as a percentage of V̇O2max (LT-% V̇O2max), and its relationship with aging. Here are the key findings related to the lactate threshold and its alterations with age:

Cross-Sectional Study on Masters Endurance Runners:

• A cross-sectional study involving masters endurance runners, ranging from 40 to over 70 years of age, was conducted. The study included 111 men and 57 women.
• LT-% V̇O2max, when expressed as a percentage of maximal oxygen uptake (V̇O2max), is considered a valuable marker for assessing endurance running performance among individuals with similar V̇O2max values.
• Interestingly, the study found that LT-% V̇O2max did not differ significantly between men and women in this age group. However, it did increase with age. This suggests that, for masters athletes with similar V̇O2max values, the lactate threshold becomes a relatively more critical determinant of endurance performance as they age.

Longitudinal Studies on Masters Athletes:

• More recent longitudinal studies involving masters athletes reported that the change in lactate threshold over a six-year follow-up was not a strong predictor of running performance when expressed as a percentage of V̇O2max.
• Similarly, another study involving both untrained men and women showed comparable results, indicating that the change in LT-% V̇O2max was not a robust predictor of performance.
• It’s important to note that in both studies, V̇O2max was lower in the older age groups. This reduction in V̇O2max in older individuals contributes to the increase in LT-% V̇O2max since LT remained relatively stable or decreased with age when expressed at absolute V̇O2 values.

Physiological Adaptations to Exercise Training in Older Adults:

Despite the natural aging process and the associated declines in body composition and exercise performance, well-trained middle-aged and older athletes can achieve remarkable performances. Moreover, older individuals who engage in exercise for general fitness can experience gains in muscular strength and endurance comparable to those seen in younger adults. Here are key insights into the physiological adaptations to exercise training in older adults:

Strength Training:

• The decline in strength that occurs with aging is influenced by a combination of the natural aging process and reduced physical activity, leading to a decrease in muscle mass and function.
• Aging does not appear to impair the ability to improve muscle strength or muscle hypertrophy through resistance training.
• Studies have demonstrated substantial strength gains and muscle hypertrophy in older individuals who engage in resistance training. For example, older men who participated in a 12-week resistance training program experienced a 107% increase in extension strength and a 227% increase in flexion strength. Muscle hypertrophy was evident through CT scans and muscle biopsies.
• Older, previously untrained men and women have shown significant increases in strength and muscle fiber cross-sectional area after engaging in resistance training programs.
• Resistance training has been shown to improve functional performance, such as chair rise time, in older individuals. This can enhance their ability to perform activities of daily living.
• Older individuals who regularly engage in resistance training tend to have higher muscle mass, lower body fat percentages, and significantly greater strength compared to their sedentary peers. Additionally, they exhibit higher bone mineral densities and maintain greater muscle strength and power when compared to age-matched aerobic exercise-trained individuals

Aerobic and Anaerobic Capacity in Older Adults:

Recent research has provided insights into the aerobic and anaerobic capacity of older adults and their responses to endurance training:

Aerobic Capacity (VO2max):

• Studies have shown that improvements in VO2max (maximal oxygen consumption) with training are similar for both younger (ages 21-25) and older (ages 60-71) men and women.
• Older individuals, despite starting with lower pretraining VO2max values on average, experienced absolute increases of 5.5 to 6.0 ml · kg–1 · min–1, which were similar to those observed in younger subjects.
• When older men and women engaged in endurance training by walking, running, or a combination of both for about 4 miles (6 kilometers) per day over 9 to 12 months, they achieved comparable increases in VO2max, averaging 21% for men and 19% for women.
• Previously sedentary older individuals appear to reach a peak in cardiovascular adaptation after three to six months of moderate training.
• These findings suggest that endurance training can produce significant gains in aerobic capacity across a wide age range, from 20 to 70 years, irrespective of age, gender, or initial fitness level. However, it’s important to note that while older individuals can improve their aerobic capacity through training, achieving performance standards equivalent to younger athletes may be challenging.

The precise mechanisms underlying the body’s adaptations to training at different ages are not fully understood. While younger subjects tend to experience improvements in VO2max associated with increased maximal cardiac output, older individuals often exhibit greater gains in muscle oxidative enzyme activities. This suggests that peripheral factors within the muscles may play a more significant role in the aerobic adaptations to training in older individuals.

Anaerobic Capacity (Lactate Threshold):

• Lactate threshold, expressed as a percentage of a person’s VO2max (LT-% VO2max), tends to increase with aging and is not strongly associated with endurance running performance in older adults.
• In contrast, in young and middle-aged adults, LT-% VO2max is a reliable predictor of endurance performance in activities such as running, cycling, swimming, and cross-country skiing.
• The differing rates of aging between the oxygen transport and lactic acid buffering systems likely contribute to this variation in the predictive value of lactate threshold for endurance performance in older individuals.
• When comparing the lactate threshold of individuals with different VO2max values, it is often more appropriate to consider the absolute VO2 value corresponding to that threshold when explaining endurance performance.

Older adults can significantly improve their aerobic capacity through endurance training, and their adaptations are similar to those observed in younger individuals. However, the role of peripheral factors in these adaptations may be more pronounced in older individuals. Additionally, lactate threshold as a percentage of VO2max may not be as strongly associated with endurance performance in older adults compared to younger and middle-aged individuals, emphasizing the importance of considering absolute VO2 values when assessing endurance capabilities in older individuals.

Sport Performance in Aging Athletes:

Sport performance is influenced by age-related changes in physiological function. Here’s an overview of how aging affects sport performance in various athletic events:

Running Performance:

• Historically, world records and national records in running events, such as the mile, have been achieved by athletes in their 20s or early 30s, suggesting that individuals are often in their physical prime during this age range.
• The world record for the mile, which stood at 3 minutes and 59.4 seconds in 1954 when Roger Bannister first broke the 4-minute barrier, has been continuously improved, with the current record set at 3 minutes and 43.13 seconds by Hicham El Guerrouj of Morocco in 1999.
• While it may have seemed inconceivable in the past, older individuals have also achieved remarkable running records. For example, Eamonn Coghlan ran a sub-4-minute mile at the age of 41, and a sub-5-minute mile was recorded by a 65-year-old individual.
• Overall, running performance tends to decline with age, and the rate of this decline appears to be independent of the race distance. Longitudinal studies of elite distance runners indicate that despite rigorous training, performance in events ranging from the mile to the marathon typically decreases at a rate of about 1.0% per year from the age of 27 to 47.
• World records for sprint runs (100 meters) and longer-distance runs (10 kilometers) also tend to decrease by about 1% per year from age 25 to age 60, with a more significant slowdown in men’s records after age 60.
• Sprint and endurance running performances exhibit similar patterns of change with aging.

Swimming Performance:

• A retrospective study of freestyle performances at the U.S. Masters swimming championships between 1991 and 1995 revealed that both men’s and women’s performances in the 1,500-meter freestyle event declined steadily from age 35 to approximately 70 years.
• After age 70, swimming times slowed at a faster rate.
• Notably, the rate and magnitude of declines in swimming performance were found to be greater for women compared to men with increasing age.

These observations highlight the age-related changes in sport performance, with performance generally declining as individuals age. However, it’s important to note that older athletes can still achieve remarkable records and compete at a high level, demonstrating the potential for athletic success at various ages. Additionally, performance decline rates can vary between sports and events, with some athletes experiencing more significant declines than others as they age.

Cycling Performance:

• Cycling performance, similar to other strength and endurance sports, typically sees record-setting achievements in the age range of 25 to 35.
• Both male and female cyclists’ records for races covering 40 kilometers (24.9 miles) show a decline in speed with increasing age, averaging about 20 seconds (approximately 0.6%) per year.
• U.S. national cycling records for 20 kilometers (12.4 miles) exhibit a similar pattern for both men and women. In this case, speed decreases by approximately 12 seconds (approximately 0.7%) per year from age 20 to nearly age 65.

Weightlifting:

• Maximal muscle strength is generally attained between the ages of 25 and 35.
• Male records for the sum of three power lifts (bench press, squat, and deadlift) demonstrate a steady decline with age, averaging about 12.1 kilograms (26.7 pounds) or approximately 1.8% per year.
• While there is a typical decline in strength with age, individual variations are significant. Some individuals may maintain or even exhibit greater strength at age 60 than those much younger.

These observations highlight the general trend of declining athletic performances as individuals age, which is consistent with the principles of human aging. However, it’s important to note that there are always exceptional individuals who defy these trends and maintain or even improve their performance as they grow older. Age-related changes in athletic performance are influenced by a combination of physiological factors, training, genetics, and individual variations.

Special Issues in Aging and Exercise: Environmental Stress

Exposure to Heat:

• Older individuals may be less tolerant of heat stress compared to younger counterparts.
• The rate of metabolic heat production is related to the absolute exercise intensity, while heat loss mechanisms depend on relative exercise intensity.
• When older and younger individuals are matched for body composition and V . O2max, there is no difference in core temperature during exercise in the heat.
• Physical training can impact thermoregulatory responses. Sweat gland density doesn’t decline significantly with aging, but sweat gland output may decrease. Sweating rate is closely related to V . O2max rather than age.
• Skin blood flow is lower in older individuals, but regular aerobic training can improve heat dissipation in older individuals.
• Exercise in the heat requires significant blood flow to both the skin and exercising muscles. Older individuals may have less effective redistribution of blood flow, but improving aerobic fitness can enhance this response.

The discussion highlights that while aging may impact heat tolerance to some extent, regular physical training, especially aerobic training, can improve thermoregulatory responses and help older individuals better cope with heat stress during exercise.

Exposure to Cold and Altitude:

• Older individuals may have reduced ability to generate metabolic heat and impaired cutaneous vasculature constriction in response to cold stress.
• Behavioral thermoregulation, such as wearing appropriate clothing, can help older athletes offset these physiological changes and exercise safely in cold environments.
• At high altitudes, older athletes are expected to respond similarly to their younger counterparts, and their performance should be comparable if they have similar physical fitness levels.

Longevity and Risk of Injury and Death:

• Studies in rats have shown mixed results regarding the influence of exercise on longevity, with caloric restriction being a more reliable factor in increasing lifespan.
• Limited data from human studies suggest that regular physical activity may increase active lifespan (compression of mortality) and potentially add a few years to life.
• As people age, they are at greater risk for injuries involving tendons, cartilage, and bones, with common orthopedic injuries including rotator cuff tears, tendon ruptures, and stress fractures.
• While injury risks may increase with age, regular exercise can also reduce the risk of falls and related injuries, making exercise beneficial for overall health.
• The risk of death during exercise does not appear to be higher in older athletes compared to younger and middle-aged athletes, but sedentary older individuals may be at increased risk due to undiagnosed or subclinical diseases.
• An active lifestyle can reduce the risk of death from chronic diseases, highlighting the importance of regular physical activity in promoting overall health and longevity.