Aerobic Capacity, Activity Levels and Daily Energy Expenditure in Male and Female Adolescents of the Kenyan Nandi Sub-Group

Ultramarathon Evaluation above 180 km in relation to Peak Age and Performance

BACKGROUND

Ultramarathons with distances over 180 km might lead to different results regarding participation, performance, and age compared to shorter runs of 50 and 100 km.

OBJECTIVE

To evaluate ultramarathons with distances above 180 km in relation to runners' peak age and performance.

METHOD

s. Verification of the quantity of competitions in runs over 180 km by continents in the period 2000 to 2020 and evaluation of the individual results of 13,300 athletes after 2010.

RESULTS

Europe stood out with the largest number of organized events, followed by Asia and North America. The age peak performance (PP) in men and women averaged 45 years old with relationship between sex × years (F = 3.612, p < 0.001; η2 = 0.003). Men accounted for more than 80% of the runners and showed a reduction in PP from 2015 onwards (p < 0.001). Competitions between 180 and 240 km were the most frequent, particularly after 2016, surpassing the number of marathons over 360 km (p < 0.001). Men and women showed higher velocity in distances (p < 0.001) from 180 to 240 km when compared to 241 to 300 k m, 301 to 360 km, and >360 km courses.

CONCLUSIONS

The decade between 2010 and 2020 showed an increase in the number of Ultramarathon running events. Europe had the highest number. Women had low participation. Performance progression fell, a fact associated with an increase in the number of participants and not specifically related to a decline in athletic performance over the years.

Trunk muscle endurance, strength and flexibility in rural subsistence farmers and urban industrialized adults in western Kenya

OBJECTIVES

High trunk muscle endurance, strength, and moderate flexibility reportedly help maintain musculoskeletal health, but there is evidence for tradeoffs among these variables as well as sex differences in trunk muscle endurance and strength. To test if these observations extend similarly to both men and women in nonindustrial and industrial environments, we investigated intra-individual associations and group and sex differences in trunk muscle endurance, strength, and flexibility among 74 (35 F, 39 M; age range: 18-61 years) adults from the same Kalenjin-speaking population in western Kenya. We specifically compared men and women from an urban community with professions that do not involve manual labor with rural subsistence farmers, including women who frequently carry heavy loads.

METHODS

Trunk muscle endurance, strength, and flexibility were measured with exercise tests and electromyography (EMG).

RESULTS

We found a positive correlation between trunk extensor strength and endurance (R = .271, p ≤ .05) and no associations between strength or endurance and flexibility. Rural women had higher trunk extensor and flexor endurance, EMG-determined longissimus lumborum endurance, and trunk extensor strength than urban women (all p ≤ .05). Rural women had higher trunk extensor and flexor endurance than rural men (both p ≤ .05). Urban women had lower trunk flexor and extensor endurance than urban men (both p ≤ .01).

CONCLUSIONS

High levels of physical activity among nonindustrial subsistence farmers, particularly head carrying among women, appear to be associated with high trunk muscle endurance and strength, which may have important benefits for helping maintain musculoskeletal health.

Inaugural HealthAccord Conference (SportAccord Convention, Bangkok, Thailand): The Power of Sport - The Power to Change

SportAccord organized the inaugural HealthAccord conference on April 19, 2018, in Bangkok, Thailand. The goal of HealthAccord is for the International Sport Federations (IF) and sport industry leaders to address high-priority issues facing sport through a serious commitment to innovation to protect athlete health, to enhance athlete performance, and to stimulate action to improve global health through the promotion of physical activity. The first HeathAccord conference was organized by drawing on the knowledge and experience of experts from global health programs focused on athletes and global citizens, respectively. The first session, "The Power of Sport," addressed the application of "state of the art" sport science and sport medicine for the protection of athlete health and to enhance sport performance. "The Power of Sport" session concentrated on enabling athletes to perform spectacular feats that are "higher, stronger, faster" intended to engage and thrill global audiences without resorting to prohibited substances and methods, to enable athletes to remain active in sport for a longer career, and to increase the attraction of sport for sponsors. In the second session, "The Power to Change," sport was viewed as having an important role in promoting physical activity within their respective federations, community, and internationally. The Olympic movement, IF, and other sport stakeholders are urgently needed to become the social drivers to correct the mismatch between physical activity for health development and draw toward sedentary lifestyles of the modern world. Key outcomes of this first HealthAccord conference were the agreement among participants to develop an innovative and high-impact collaboration between IF and related stakeholders; to use sport as a social movement platform to measurably improve health, both for athletes and for global citizens.

Brain oxygenation declines in elite Kenyan runners during a maximal interval training session

PURPOSE

The purpose of this study was to characterise the cerebral oxygenation (Cox) response during a high-intensity interval training session in Kenyan runners, and to examine any relationship with running performance.

METHODS

15 Kenyan runners completed a 5-km time trial (TT) and a Fatigue Training Test on a treadmill (repeated running bouts of 1-km at a pace 5% faster than their mean 5-km TT pace with a 30-s recovery until exhaustion). Changes in Cox were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxy-haemoglobin (Δ[O₂Hb] and Δ[HHb]), tissue oxygenation index (TOI), and total hemoglobin index (nTHI).

RESULTS

The number of 1-km repetitions achieved by the participants was 5.5 ± 1.2 repetitions at a mean pace of 20.5 ± 0.7 km h^-1. Δ[O₂Hb] measured at the end of each running repetition declined progressively over the course of the trial (p = 0.01, ES = 4.59). Δ[HHb] increased during each running bout until the end of the Fatigue Training Test (p < 0.001; ES = 6.0). TOI decreased significantly from the beginning of the test (p = 0.013, ES = 1.83), whereas nTHI remained stable (ES = 0.08). The Cox decline in the Fatigue Training Test was negatively correlated with the speed at which the test was completed (p = 0.017; r = -0.61), suggesting that the best performers were able to defend their Cox better than those of lower running ability.

CONCLUSIONS

In conclusion, this study suggests that elite Kenyan runners cannot defend cerebral oxygenation when forced to exercise to their physiological limits. This emphasises the critical importance of pacing in their racing success.

Patterns and Associated Factors of Physical Activity among Adolescents in Nigeria

INTRODUCTION

Understanding the context where adolescents' physical activity (PA) takes place could impact a more targeted approach to implement PA promotion and interventions in Africa. However, standardized data on adolescents' PA behaviour is lacking in Nigeria. We described PA patterns in the various domains (home, school, transport, leisure-time) and intensity categories (light-intensity PA, moderate- to vigorous- intensity physical activity [MVPA] and total PA), and their associations with sociodemographic factors and socioeconomic status (SES) among secondary school adolescents in Nigeria.

METHODS

A cross-sectional survey was conducted in a representative sample of 1006 secondary school adolescents (12-18 years, 50.4% girls) in Maiduguri, Nigeria. Self-reported PA was assessed with an adapted version of the Activity Questionnaire for Adolescents and Young Adults. Outcomes were weekly minutes (min/wk) of PA spent in the various domains and intensity categories. Multivariate ANOVA was used to examine associations of PA scores (domains and intensity levels) with adolescents' sociodemographic characteristics and SES, and track differences in PA scores between subgroups.

RESULTS

The total sample reported most PA at school (1525 min/wk), the least during active transportation (210 min/wk), and only 37% engaged in 60 min of MVPA daily. Boys reported significantly more leisure-time PA (P<0.001), active transportation (P<0.001), MVPA (P = 0.023) and total PA (P = 0.003) than girls, while girls reported more school-based PA (P = 0.009), home-based PA (P<0.001) and light-intensity PA (P<0.001) than boys. Moderate-intensity PA (P = 0.024) and total PA (P = 0.049) were significantly higher in younger age group than in older group. Household car ownership was associated with less active transportation (P = 0.009), less moderate-intensity PA (P = 0.048) and with more leisure-time PA (P = 0.013). High parental SES was associated with more leisure-time PA (P = 0.002), more MVPA (P = 0.047) and less active transportation (P<0.001). Adolescents of various weight status differed significantly in their leisure-time PA (P<0.001), moderate-intensity PA (P = 0.011) and total PA (P = 0.033).

CONCLUSIONS

The patterns and levels of physical activity among adolescents in Nigeria vary according to the adolescents' age, gender, weight status and SES. These findings have important public health implications for identifying subgroups of Nigerian adolescents that should be targeted for effective physical activity promoting interventions.

Variation in Foot Strike Patterns among Habitually Barefoot and Shod Runners in Kenya

Runners are often categorized as forefoot, midfoot or rearfoot strikers, but how much and why do individuals vary in foot strike patterns when running on level terrain? This study used general linear mixed-effects models to explore both intra- and inter-individual variations in foot strike pattern among 48 Kalenjin-speaking participants from Kenya who varied in age, sex, body mass, height, running history, and habitual use of footwear. High speed video was used to measure lower extremity kinematics at ground contact in the sagittal plane while participants ran down 13 meter-long tracks with three variables independently controlled: speed, track stiffness, and step frequency. 72% of the habitually barefoot and 32% of the habitually shod participants used multiple strike types, with significantly higher levels of foot strike variation among individuals who ran less frequently and who used lower step frequencies. There was no effect of sex, age, height or weight on foot strike angle, but individuals were more likely to midfoot or forefoot strike when they ran on a stiff surface, had a high preferred stride frequency, were habitually barefoot, and had more experience running. It is hypothesized that strike type variation during running, including a more frequent use of forefoot and midfoot strikes, used to be greater before the introduction of cushioned shoes and paved surfaces.

Maintained cerebral oxygenation during maximal self-paced exercise in elite Kenyan runners

The purpose of this study was to analyze the cerebral oxygenation response to maximal self-paced and incremental exercise in elite Kenyan runners from the Kalenjin tribe. On two separate occasions, 15 elite Kenyan distance runners completed a 5-km time trial (TT) and a peak treadmill speed test (PTS). Changes in cerebral oxygenation were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxyhemoglobin (Δ[O2Hb] and Δ[HHb]), tissue oxygenation index (TOI), and total hemoglobin index (nTHI). During the 5-km TT (15.2 ± 0.2 min), cerebral oxygenation increased over the first half (increased Δ[O2Hb] and Δ[HHb]) and, thereafter, Δ[O2Hb] remained constant (effect size, ES = 0.33, small effect), whereas Δ[HHb] increased until the end of the trial ( P < 0.05, ES = 3.13, large effect). In contrast, during the PTS, from the speed corresponding to the second ventilatory threshold, Δ[O2Hb] decreased ( P < 0.05, ES = 1.51, large effect), whereas Δ[HHb] continued to increase progressively until exhaustion ( P < 0.05, ES = 1.22, large effect). Last, the TOI was higher during the PTS than during the 5-km TT ( P < 0.001, ES = 3.08; very large effect), whereas nTHI values were lower ( P < 0.001, ES = 2.36, large effect). This study shows that Kenyan runners from the Kalenjin tribe are able to maintain their cerebral oxygenation within a stable range during a self-paced maximal 5-km time trial, but not during an incremental maximal test. This may contribute to their long-distance running success.

A systematic review of active transportation research in Africa and the psychometric properties of measurement tools for children and youth

Background

Previous systematic reviews indicate that active transportation (AT; the use of non-motorized travel modes such as walking, running and cycling) is an important source of daily physical activity (PA). However, no previous systematic review has examined travel behaviours among African children and youth or the psychometric properties of measurement tools used among children and youth worldwide.

Methods

Studies on AT among African children and youth (aged 5–17 years) were identified through 1) the MEDLINE and Embase databases; 2) manual searches of six African journals that are not indexed in these databases; and 3) the articles included in a previous systematic review on PA among children and youth in Sub-Saharan Africa. Second, literature on the psychometric properties of measurement tools for children and youth was searched using the MEDLINE, Embase, Cochrane Central Register of Controlled Trials, PsycInfo, SportDiscus, and Health and Psychosocial Instruments databases. Study quality was assessed with a modified version of the Downs and Black checklist.

Results

Twenty studies reported original data on AT among African children and youth. This evidence suggests that rates of AT to/from school are lower in urban areas and in youth attending higher SES schools. Two population-based studies reported rates of AT ranging between 19.8% and 66.6% in multiple countries. Studies conducted in Africa seldom examined non-school travel and only one reported data on the psychometric properties of their measures of travel behaviours. Nineteen studies conducted predominantly in high-income countries provided psychometric data. Child and parent reports were used in 17 studies, and these measures generally showed substantial to almost perfect test-retest reliability and convergent validity for school trips. Limited information was available regarding non-school trips. Objective measures of travel behaviours have been used much less often, and further validity and reliability assessments are warranted.

Conclusion

These findings emphasize a need for more research examining travel behaviours among African children and youth, particularly for non-school travel. Further research is needed to develop valid and reliable measures of non-school travel and to examine their psychometric properties in the African context. These measures could then be used to evaluate AT promotion interventions.

Objectively measured habitual physical activity and sedentary behaviour in obese and non-obese Malaysian children

The present study examined objectively measured physical activity in Malaysian children and compared the differences in physical levels between obese and healthy weight children. Eighty-six obese children were matched for age and sex with 86 healthy weight children with median age 9.5 years. Habitual physical activity and sedentary behaviour were measured over 5 days using Actigraph accelerometers. Time spent sedentary was significantly higher in the obese group (90% vs. 86% of daytime; p = 0.001). Moderate-to-vigorous-intensity physical activity was significantly higher in the healthy weight group (1.2 vs. 0.7% of daytime, p < 0.001). In both healthy weight and obese children, physical activity levels were exceptionally low, although moderate-to-vigorous-intensity physical activity was significantly lower in the obese group than the healthy weight group. Efforts to prevent and treat obesity in Malaysian children will need a substantial focus on the promotion of reductions in sedentary behaviour and increases in physical activity.

Lean body mass can predict lung function in underweight and normal weight sedentary female young adults

BACKGROUND

A previous cross-sectional study found reduced lung function among over weight and obese students in Zanjan city. However, there is no reliable evidence about the respiratory function of underweight and normal weight students. The objective of this study was to evaluate lung function and develop prediction equations in underweight and normal weight female young adults residing in Soltanieh city near Zanjan.

MATERIALS AND METHODS

A cross sectional study was conducted on underweight (n=29, mean age=16±0.84 years) and normal weight (n=38, mean age=15.9±0.86 years) sedentary female young adults. Fat mass (FM) was measured by Omron Body Fat Monitor FB-3002. Lean body mass (LBM), waist to hip ratio (WHR), body mass index (BMI) and waist circumference (WC) were calculated. Maximum oxygen uptake was calculated using Queen's College step test. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were recorded, using Spirolab III spirometer. Independent t test, Pearson's correlation test and stepwise linear regression analysis were used for data analysis.

RESULTS

FVC and FEV1 were significantly lower than the reference values in both groups (P<0.05). LBM was significantly correlated with FVC and FEV1 in underweight and normal weight groups (P<0.05). Regression equations were derived to predict FVC and FEV1 using LBM.

CONCLUSION

This study suggests that dynamic lung functions are poor in underweight and normal weight sedentary female young adults residing in Soltanieh city and LBM plays a significant role in their lung function.