Genotypes and Distance Running

Analysis of over 1 million race records shows runners from East African countries as the fastest in 50-km ultra-marathons

The 50-km ultra-marathon is a popular race distance, slightly longer than the classic marathon distance. However, little is known about the country of affiliation and age of the fastest 50-km ultra-marathon runners and where the fastest races are typically held. Therefore, this study aimed to investigate a large dataset of race records for the 50-km distance race to identify the country of affiliation and the age of the fastest runners as well as the locations of the fastest races. A total of 1,398,845 50-km race records (men, n = 1,026,546; women, n = 372,299) were analyzed using both descriptive statistics and advanced regression techniques. This study revealed significant trends in the performance of 50-km ultra-marathoners. The fastest 50-km runners came from African countries, while the fastest races were found to occur in Europe and the Middle East. Runners from Ethiopia, Lesotho, Malawi, and Kenya were the fastest in this race distance. The fastest 50-km racecourses, providing ideal conditions for faster race times, are in Europe (Luxembourg, Belarus, and Lithuania) and the Middle East (Qatar and Jordan). Surprisingly, the fastest ultra-marathoners in the 50-km distance were found to fall into the age group of 20-24 years, challenging the conventional belief that peak ultra-marathon performance comes in older age groups. These findings contribute to a better understanding of the performance models in 50-km ultra-marathons and can serve as valuable insights for runners, coaches, and race organizers in optimizing training strategies and racecourse selection.

Genomic profile in association with sport-type, sex, ethnicity, psychological traits and sport injuries of elite athletes: review and future perspectives

In the last few years, some inherited determinants have been associated with elite athletic performance, but its polygenic trait character has limited the correct definition of elite athlete's genomic profile. This qualitative descriptive study aims to summarise the current understanding about genetic and epigenetic factors in elite athletes, as well as their genomic profile in association with sport-type, sex, ethnicity, psychological traits and sport injuries. A narrative review of the literature across a broad cross-section of the elite athletes' genomic profile was undertaken. Elite performance relies on rare gene variants within a great interface between molecular, cellular and behavioural sport-related phenotypes and the environment, which is still poorly understood. ACTN3 rs1815739 and ACE I/D polymorphisms appear to be associated to specific sprint phenotypes and influence the athletic status, i.e., the rs1815739 variant is more influential to 200-m performance and the ACE ID polymorphism is more involved in the longer, 400-m sprint performance. Generally, athletes show endurance-based sports characteristics or power-based sports characteristics, but some studies have reported some genes associations to both sports-based characteristics. Furthermore, genetic studies with larger cohorts of single-sport athletes might be preferable than studies combining athletes of different sports, given the existence of distinct athlete profiles and sport demands. Athletic performance may be influenced by the serotonergic pathway and the potential injury risk (namely stress fracture) might be associated to a genetic predisposition associated to the mechanical loading from the intense physical exercise. The study of gene variants associated to sex and ethnicity-related to athletic performance needs further investigation. The combination of genome-wide association studies addressing the genetic architecture of athletes and the subsequent replication and validation studies might for additional genetic data is mandatory.

The "New York City Marathon": participation and performance trends of 1.2M runners during half-century

The aim of the present study was to examine trends in participation, performance, age and nationality during a ~ 50-years period in the largest dataset ever studied in the "New York City Marathon". We analysed 1,174,331 finishers (women, n= 349,145, age 39.7 ± 8.7 years; men, n= 825,186, 41.7 ± 9.2 years). The overall participation increased across calendar years for all nationalities, and this increase was more pronounced in women, which resulted in a decreasing men-to-women ratio. Men were faster and older than women. Ethiopians and Kenyans were the fastest and youngest in women and men, respectively. Japanese were the slowest and Germans were the oldest in both sexes. Race time increased across years. Coaches and fitness trainers should be aware of these trends and should emphasize the development of training programs for older and slower runners.

Russians are the fastest 100-km ultra-marathoners in the world

Objectives

A recent study investigating the top 10 100-km ultra-marathoners by nationality showed that Japanese runners were the fastest worldwide. This selection to top athletes may lead to a selection bias and the aim of this study was to investigate from where the fastest 100-km ultra-marathoners originate by considering all finishers in 100-km ultra-marathons since 1959.

Methods

We analysed data from 150,710 athletes who finished a 100-km ultra-marathon between 1959 and 2016. To get precise estimates and stable density plots we selected only those nationalities with 900 and more finishes resulting in 24 nationalities. Histograms and density plots were performed to study the distribution of race time. Crude mean, standard deviation, median, interquartile range (IQR), mode, skewness and excess of time for each nationality were computed. A linear regression analysis adjusted by sex, age and year was performed to study the race time between the nationalities. Histograms, density and scatter plots showed that some races seemed to have a time limit of 14 hours. From the complete dataset the finishes with more than 14 hours were removed (truncated dataset) and the same descriptive plots and analysis as for the complete dataset were performed again. In addition to the linear regression a truncated regression was performed with the truncated dataset to allow conclusion for the whole sample. To study a potential difference between races at home and races abroad, an interaction term race site home/abroad with nationality was included in the model.

Results

Most of the finishes were achieved by runners from Japan, Germany, Switzerland, France, Italy and USA with more than 260’000 (85%) finishes. Runners from Russia and Hungary were the fastest and runners from Hong Kong and China were the slowest finishers.

Conclusion

In contrast to existing findings investigating the top 10 by nationality, this analysis showed that ultra-marathoners from Russia, not Japan, were the fastest 100-km ultra-marathoners worldwide when considering all races held since 1959.

Marathon Specialization in Elites: A Head Start for Africans

PURPOSE

To assess differences in event-specific specialization between elite African and non-African male marathon runners based on age, performance, and career length.

METHODS

The top 90 African marathoners from 2001 to 2015 were compared with the top 90 non-African marathoners from the same time period across various markers related to specialization age, performance, and career length. Independent t tests were used to identify significant differences (P < .05) between the African and non-African groups. Linear regression was used to explore the relationship between first half-marathon and best full-marathon performance. A 1-way ANOVA and Bonferroni correction was used to assess differences in specialization age and rates of performance improvement and decline.

RESULTS

African marathoners were found to specialize, reach peak levels of performance, and retire at younger ages than non-African marathoners (P < .001). In addition, African marathoners were found to be faster at these same career time points and in half-marathon performance (P < .001). There was no significant difference in the number of career marathons run between groups, but African marathoners were found to race more frequently than non-African marathoners (P < .001). Half-marathon performance was positively correlated with marathon performance (r² = .67). Marathon athletes who specialized at early ages experienced significantly higher rates of improvement than those who specialized at older ages. (P < .05).

CONCLUSIONS

The findings suggest that elite African marathoners achieve a greater level of performance at younger ages than their non-African counterparts. Furthermore, current marathon talent-identification practice may benefit from using half-marathon performance.

Why nature prevails over nurture in the making of the elite athlete

While the influence of nature (genes) and nurture (environment) on elite sporting performance remains difficult to precisely determine, the dismissal of either as a contributing factor to performance is unwarranted. It is accepted that a complex interaction of a combination of innumerable factors may mold a talented athlete into a champion. The prevailing view today is that understanding elite human performance will require the deciphering of two major sources of individual differences, genes and the environment. It is widely accepted that superior performers are endowed with a high genetic potential actualised through hard and prodigious effort. Heritability studies using the twin model have provided the basis to disentangle genetic and environmental factors that contribute to complex human traits and have paved the way to the detection of specific genes for elite sport performance. Yet, the heritability for most phenotypes essential to elite human performance is above 50% but below 100%, meaning that the environment is also important. Furthermore, individual differences can potentially also be explained not only by the impact of DNA sequence variation on biology and behaviour, but also by the effects of epigenetic changes which affect phenotype by modifying gene expression. Despite this complexity, the overwhelming and accumulating evidence, amounted through experimental research spanning almost two centuries, tips the balance in favour of nature in the “nature” and “nurture” debate. In other words, truly elite-level athletes are built – but only from those born with innate ability.

Performance and age of African and non-African runners in World Marathon Majors races 2000-2014

The age for the fastest marathoners is well investigated, but not the age and nationality of the fastest. We investigated the age of peak marathon performance for the annual top 100 women and men competing in four races of the "World Marathon Majors" (Boston, Berlin, Chicago and New York) and the "Stockholm Marathon" between 2000 and 2014 using mixed-effects regression analyses and one-way ANOVA. Race times of Ethiopian men decreased to 2:14 h:min, but remained unchanged for Kenyan (2:14 h:min), Moroccan (2:15 h:min) and South African (2:18 h:min) men. Race times in Ethiopian (2:34 h:min), Kenyan (2:29 h:min) and South African (2:49 h:min) women showed no changes. Age increased in Ethiopian and South African men to 29.0 ± 5.0 and 32.0 ± 1.0 years, respectively. Age for Kenyan (29.9 ± 2.0 years) and Moroccan (34.9 ± 3.9 years) men remained unchanged. Age remained unchanged for Ethiopian (26.5 ± 2.0 years), Kenyan (30.0 ± 0.8 years) and South African (36.3 ± 7.0 years) women. In summary, Ethiopian men improved marathon race times, but not Ethiopian women. Age increased in Ethiopian men, but not in Ethiopian women. For practical applications, female and male marathoners from Ethiopia were the youngest and the fastest.

The heritable path of human physical performance: from single polymorphisms to the "next generation"

Human physical performance is a complex multifactorial trait. Historically, environmental factors (e.g., diet, training) alone have been unable to explain the basis of all prominent phenotypes for physical performance. Therefore, there has been an interest in the study of the contribution of genetic factors to the development of these phenotypes. Support for a genetic component is found with studies that shown that monozygotic twins were more similar than were dizygotic twins for many physiological traits. The evolution of molecular techniques and the ability to scan the entire human genome enabled association of several genetic polymorphisms with performance. However, some biases related to the selection of cohorts and inadequate definition of the study variables have complicated the already difficult task of studying such a large and polymorphic genome, often resulting in inconsistent results about the influence of candidate genes. This review aims to provide a critical overview of heritable genetic aspects. Novel molecular technologies, such as next-generation sequencing, are discussed and how they can contribute to improving understanding of the molecular basis for athletic performance. It is important to ensure that the large amount of data that can be generated using these tools will be used effectively by ensuring well-designed studies.

Genetic aspects of athletic performance: the African runners phenomenon

The current dominance of African runners in long-distance running is an intriguing phenomenon that highlights the close relationship between genetics and physical performance. Many factors in the interesting interaction between genotype and phenotype (eg, high cardiorespiratory fitness, higher hemoglobin concentration, good metabolic efficiency, muscle fiber composition, enzyme profile, diet, altitude training, and psychological aspects) have been proposed in the attempt to explain the extraordinary success of these runners. Increasing evidence shows that genetics may be a determining factor in physical and athletic performance. But, could this also be true for African long-distance runners? Based on this question, this brief review proposed the role of genetic factors (mitochondrial deoxyribonucleic acid, the Y chromosome, and the angiotensin-converting enzyme and the alpha-actinin-3 genes) in the amazing athletic performance observed in African runners, especially the Kenyans and Ethiopians, despite their environmental constraints.

What performance characteristics determine elite versus nonelite athletes in the same sport?

Context:

There are significant data comparing elite and nonelite athletes in anaerobic field and court sports as well as endurance sports. This review delineates specific performance characteristics in the elite athlete and may help guide rehabilitation.

Evidence Acquisition:

A Medline search from April 1982 to April 2012 was undertaken for articles written in English. Additional references were accrued from reference lists of research articles.

Results:

In the anaerobic athlete, maximal power production was consistently correlated to elite performance. Elite performance in the endurance athlete is more ambiguous, however, and appears to be related to the dependent variable investigated in each individual study.

Conclusion:

In anaerobic field and court sport athletes, maximal power output is most predictive of elite performance. In the endurance athlete, however, it is not as clear. Elite endurance athletes consistently test higher than nonelite athletes in running economy, anaerobic threshold, and VO_2max.

Performance and age of African and non-African runners in half- and full marathons held in Switzerland, 2000-2010

Background

Endurance running performance of African (AF) and non-African (NAF) athletes is investigated, with better performances seen for Africans. To date, no study has compared the age of peak performance between AF and NAF runners. The present research is an analysis of the age and running performance of top AF and NAF athletes, using the hypothesis that AF athletes were younger and faster than NAF athletes.

Methods

Age and performance of male and female AF and NAF athletes in half-marathons and marathons held in Switzerland in 2000–2010 were investigated using single and multilevel hierarchical regression analyses.

Results

For half-marathons, male NAF runners were older than male AF runners (P = 0.02; NAF, 31.1 years ± 6.4 years versus AF, 26.2 years ± 4.9 years), and their running time was longer (P = 0.02; NAF, 65.3 minutes ± 1.7 minutes versus AF, 64.1 minutes ± 0.9 minutes). In marathons, differences between NAF and AF male runners in age (NAF, 33.0 years ± 4.8 years versus AF, 28.6 years ± 3.8 years; P < 0.01) and running time (NAF, 139.5 minutes ± 5.6 minutes versus AF, 133.3 minutes ± 2.7 minutes; P < 0.01) were more pronounced. There was no difference in age (NAF, 31.0 years ± 7.0 years versus AF, 26.7 years ± 6.0 years; P > 0.05) or running time (NAF, 75.0 minutes ± 3.7 minutes versus AF, 75.6 minutes ± 5.3 minutes; P > 0.05) between NAF and AF female half-marathoners. For marathoners, NAF women were older than AF female runners (P = 0.03; NAF, 31.6 years ± 4.8 years versus AF, 27.8 years ± 5.3 years), but their running times were similar (NAF, 162.4 minutes ± 7.2 minutes versus AF, 163.0 minutes ± 7.0 minutes; P > 0.05).

Conclusion

In Switzerland, the best AF male half-marathoners and marathoners were younger and faster than the NAF counterpart runners. In contrast to the results seen in men, AF and NAF female runners had similar performances. Future studies need to investigate performance and age of AF and NAF marathoners in the World Marathon Majors Series.

Genomics of elite sporting performance: what little we know and necessary advances

Numerous reports of genetic associations with performance-related phenotypes have been published over the past three decades but there has been limited progress in discovering and characterising the genetic contribution to elite/world-class performance, mainly owing to few coordinated research efforts involving major funding initiatives/consortia and the use primarily of the candidate gene analysis approach. It is timely that exercise genomics research has moved into a new era utilising well-phenotyped, large cohorts and genome-wide technologies--approaches that have begun to elucidate the genetic basis of other complex traits/diseases. This review summarises the most recent and significant findings from sports genetics and explores future trends and possibilities.

European dominance in multistage ultramarathons: an analysis of finisher rate and performance trends from 1992 to 2010

BACKGROUND

Participation and performance trends regarding the nationality of ultraendurance athletes have been investigated in the triathlon, but not in running. The present study aimed to identify the countries in which multistage ultramarathons were held around the world and the nationalities of successful finishers.

METHODS

Finisher rates and performance trends of finishers in multistage ultramarathons held worldwide between 1992 and 2010 were investigated.

RESULTS

Between 1992 and 2010, the bulk of multistage ultramarathons were held in Germany and France, with more than 30 races organized in each country. Completion rates for men and women increased exponentially, with women representing on average 16.4% of the total field. Since 1992, 6480 athletes have competed in Morocco, 2538 in Germany, and 1842 in France. A total of 81.9% of athletes originated from Europe, and more specifically from France (22.9%), Great Britain (18.0%), and Germany (13.4%).

CONCLUSION

European ultramarathoners dominated the athletes who completed multistage ultramarathons worldwide, with specific dominance of French, British, and German athletes. Future studies should investigate social aspects, such as sport tourism, among European athletes to understand why European athletes are so interested in participating in multistage ultramarathons.

Participation and performance trends in multistage ultramarathons-the 'Marathon des Sables' 2003-2012

BACKGROUND

The purpose of this study was to investigate participation and performance changes in the multistage ultramarathon 'Marathon des Sables' from 2003 to 2012.

METHODS

Participation and performance trends in the four- or six-stage running event covering approximately 250 km were analyzed with special emphasis on the nationality and age of the athletes. The relations between gender, age, and nationality of finishers and performance were investigated using regression analyses and analysis of variance.

RESULTS

Between 2003 and 2012, a number of 7,275 athletes with 938 women (12.9%) and 6,337 men (87.1%) finished the Marathon des Sables. The finisher rate in both women (r2 = 0.62) and men (r2 = 0.60) increased across years (p < 0.01). Men were significantly (p < 0.01) faster than women for overall finishers (5.9 ± 1.6 km·h-1 versus 5.1 ± 1.3 km·h-1) and for the top three finishers (12.2 ± 0.4 km·h-1 versus 8.3 ± 0.6 km·h-1). The gender difference in running speed of the top three athletes decreased (r2 = 0.72; p < 0.01) from 39.5% in 2003 to 24.1% in 2012 with a mean gender difference of 31.7 ± 2.0%. In men, Moroccans won nine of ten competitions, and one edition was won by a Jordanian athlete. In women, eight races were won by Europeans (France five, Luxembourg two, and Spain one, respectively), and two events were won by Moroccan runners.

CONCLUSIONS

The finisher rate in the Marathon des Sables increased this last decade. Men were significantly faster than women with a higher gender difference in performance compared to previous reports. Social or cultural inhibitions may determine the outcome in this event. Future studies need to investigate participation trends regarding nationalities and socioeconomic background, as well as the motivation to compete in ultramarathons.

Kenyan and Ethiopian distance runners: what makes them so good?

Since the 1968 Mexico City Olympics, Kenyan and Ethiopian runners have dominated the middle- and long-distance events in athletics and have exhibited comparable dominance in international cross-country and road-racing competition. Several factors have been proposed to explain the extraordinary success of the Kenyan and Ethiopian distance runners, including (1) genetic predisposition, (2) development of a high maximal oxygen uptake as a result of extensive walking and running at an early age, (3) relatively high hemoglobin and hematocrit, (4) development of good metabolic "economy/efficiency" based on somatotype and lower limb characteristics, (5) favorable skeletal-muscle-fiber composition and oxidative enzyme profile, (6) traditional Kenyan/Ethiopian diet, (7) living and training at altitude, and (8) motivation to achieve economic success. Some of these factors have been examined objectively in the laboratory and field, whereas others have been evaluated from an observational perspective. The purpose of this article is to present the current data relative to factors that potentially contribute to the unprecedented success of Kenyan and Ethiopian distance runners, including recent studies that examined potential links between Kenyan and Ethiopian genotype characteristics and elite running performance. In general, it appears that Kenyan and Ethiopian distance-running success is not based on a unique genetic or physiological characteristic. Rather, it appears to be the result of favorable somatotypical characteristics lending to exceptional biomechanical and metabolic economy/efficiency; chronic exposure to altitude in combination with moderate-volume, high-intensity training (live high + train high), and a strong psychological motivation to succeed athletically for the purpose of economic and social advancement.

European athletes dominate performances in Double Iron ultra-triathlons--a retrospective data analysis from 1985 to 2010

We investigated the participation and performance trends of ultra-endurance triathletes from all nationalities competing in a Double Iron ultra-triathlon (7.6-km swim, 360-km cycle and 84.4-km run) from 1985 to 2010. A total of 1854 athletes participated in 92 Double Iron ultra-triathlons. The majority of the winners came from Europe with 72 victories, followed by North America with 17 victories. The race time for the European ultra-triathletes was 1340 (s=95.3) min, decreasing highly significantly (r (2)=0.28; P<0.0001) across the years. North American ultra-triathletes finished the races within 1556 (s=124.5) min; their race time showed no changes across the years (r (2)=0.045; P=0.07). The race time for the Europeans was highly significantly faster compared to the North Americans (P<0.0001). Future studies should investigate each country in Europe and North America in order to find the country with the largest participation of athletes and their best performance.

No association between ACE gene variation and endurance athlete status in Ethiopians

PURPOSE

The most widely studied candidate gene for endurance performance is the angiotensin-converting enzyme (ACE) gene. The best endurance runners in the world hail from Kenya and Ethiopia, so the lack of association between the ACE gene and elite endurance athlete status we previously reported in Kenyans requires replication in Ethiopians.

METHODS

DNA was extracted from buccal swabs collected from subjects filling four groups: elite endurance runners from the Ethiopian national athletics team specializing in 5 km to marathon distances (n = 76), controls demographically matched to the elite endurance athletes (n = 410), controls representing the general Ethiopian population (n = 317), and sprint and power event athletes from the Ethiopian national athletics team (n = 38). ACE I/D and A22982G (rs4363) genotype frequencies were determined for each of these groups, and differences between groups were assessed using χ(2) tests.

RESULTS

There were no significant deviations from Hardy-Weinberg equilibrium in endurance athletes or either control group. Endurance athletes did not differ significantly in ACE I/D genotype frequency when compared with the endurance athlete-matched control group (P = 0.16), general controls (P = 0.076), or sprint and power athletes (P = 0.39) (endurance athletes: 15.8% II, endurance athlete-matched controls: 8.8% II, general controls: 7.6% II, sprint and power athletes: 10.5% II). Similarly, no significant differences were found in ACE A22982G genotype between groups (endurance athletes: 13.2% AA, endurance athlete-matched controls: 12.2% AA, general controls: 12.0% AA, sprint and power athletes: 13.2%; endurance athletes vs endurance athlete-matched controls: P = 0.97, endurance athletes vs general controls: P = 0.95, endurance athletes vs sprint and power athletes: P = 0.52).

CONCLUSIONS

As previously shown in elite Kenyan athletes, ACE I/D and A22982G polymorphisms are not associated with elite endurance athlete status in Ethiopians.

Food and macronutrient intake of elite Ethiopian distance runners

Background

Explanations for the phenomenal success of East African distance runners include unique dietary practices. The aim of the present study was to assess the food and macronutrient intake of elite Ethiopian distance runners during a period of high intensity exercise training at altitude and prior to major competition.

Methods

The dietary intake of 10 highly-trained Ethiopian long distance runners, living and training at high altitude (approximately 2400 m above sea level) was assessed during a 7 day period of intense training prior to competition using the standard weighed intake method. Training was also assessed using an activity/training diary.

Results

Body mass was stable (i.e., was well maintained) over the assessment period (pre: 56.7 ± 4.3 kg vs. post: 56.6 ± 4.2 kg, P = 0.54; mean ± SD). The diet comprised of 13375 ± 1378 kJ and was high in carbohydrate (64.3 ± 2.6%, 545 ± 49 g, 9.7 ± 0.9 g/kg). Fat and protein intake was 23.3 ± 2.1% (83 ± 14 g) and 12.4 ± 0.6% (99 ± 13 g, 1.8 ± 0.2 g/kg), respectively. Fluid intake comprised mainly of water (1751 ± 583 mL), while no fluids were consumed before or during training with only modest amounts being consumed following training.

Conclusions

Similar to previous studies in elite Kenyan distance runners, the diet of these elite Ethiopian distance runners met most recommendations of endurance athletes for macronutrient intake but not for fluid intake.

Relationship of running intensity to hypertension, hypercholesterolemia, and diabetes

PURPOSE

To estimate the independent relationships of running intensity with antihypertensive, LDL-cholesterol-lowering, and antidiabetic medication use when adjusted for running volume (km x d(-1)).

METHODS

Self-reported medication use was compared cross-sectionally to running pace (m x s(-1) during usual run) in 25,552 male and 29,148 female National Runners' Health Study participants.

RESULTS

The men ran a mean +/- SD of 5.2 +/- 3.1 km x d(-1) at 3.3 +/- 0.5 m x s(-1) (8.3 +/- 1.4 min x mile(-1)) and the women 4.7 +/- 2.9 km x wk(-1) at 3.0 +/- 0.4 m x s(-1) (9.2 +/- 1.8 min x mile(-1)). When adjusted for kilometers per day, each meter-per-second increment in intensity in men and women reduced the odds for antihypertensive drug use by 54% and 46%, respectively, reduced the odds for LDL-cholesterol-lowering medication use by 55% and 48%, respectively, and reduced the odds for antidiabetic medication use by 50% and 75%, respectively (all P < 0.0001). Compared with men who ran slower than 10 min x mile(-1), the odds for medication use in those who ran or exceeded a 7-min x mile(-1) pace were 72% less for antihypertensive, 78% less for LDL-cholesterol lowering, and 67% less for antidiabetic medications (the corresponding odds reductions in women were 61%, 64%, and 87%, respectively, for 8 min x mile(-1) or faster versus slower than 11 min x mile(-1)). Although usual running pace correlated significantly with a 10-km performance (male, r = 0.55; females, r = 0.49), usual pace remained significantly related to lower use of all three medications in men and antihypertension and antidiabetic medications in women when adjusted for a 10-km performance.

CONCLUSIONS

Although these results do not prove causality, they show that exercise intensity is inversely associated with the prevalence of hypertension, hypercholesterolemia, and diabetes independent of exercise volume and cardiorespiratory fitness (10-km performance), suggesting that the more vigorous the exercise, the healthier the health benefits.