Long distance running in Ethiopian athletes: a search for optimal altitude training.
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Date
2018
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Abstract
ABSTRACT
Background
The extended dominance of Ethiopian and Kenyan middle- and long- distance athletes in world
athletics has resulted in researchers proposing numerous explanations to explain this success.
Genetic predisposition, anthropometric, physiological, biochemical and biomechanical
characteristics, environmental factors like living and training at high altitude, active lifestyles
during childhood as well as nutritional practices, have all been major focus areas of past studies
that involved east African endurance athletes. Of all the proposed variables, researchers have
acknowledged the positive role of environmental factors in the success of these athletes. Despite
the past attempts to investigate the major factors that contributed to the successes of east African
athletes, to the best of the authors’ knowledge, limited studies have addressed each of the
proposed physiological and environmental variables in the Ethiopian athletes, compared with the
number of studies conducted on Kenyan athletes.
Purpose
The primary purpose of this research was to test a natural altitude training model and examine
whether it enhanced the long-distance performance of junior Ethiopian athletes. The research
also examined a variety of environmental factors associated with these junior athletes that
included daily distance travelled to and from school, mode of transport to and from school as
well as physical activity patterns after school. These factors were compared between the junior
athletes who participated in the altitude training study, current and retired World and Olympic
level long-distance Ethiopian athletes. The energy intake, macronutrient breakdown and energy
expenditure of the junior athletes during the altitude training camp were also analysed.
Methods
Demographic Characteristics Study: A total of 83 endurance runners were involved in this
study. The athletes were classified into three separate groups based on their current performance
status and age as retired elite (n = 32), current elite (n = 31) and academy junior athletes (n = 20).
The average ages of the athletes in the three groups were 38±7.6, 25±4.5, and 18±1.2 years for
retired elite, current elite and junior group athletes, respectively. The study primarily employed a
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questionnaire survey design to gather the demographic characteristics of the athletes. Along with
the questionnaire, the altitudes where the athletes were born and trained, as well as the home to
school distance of the athletes were measured. Data were collected from the retired athletes
through both self- and interviewer-administered questionnaires and forms. Self-administered
questionnaires were used to collect data from the current elite and academy junior athletes. Only
46.8% of the retired elites (n=15) filled in the questionnaire and the rest 53.2% (n=17) of the
retired elite athletes responded to the questionnaire via telephone. The home to school distance
of 71.8% (n = 23) and 58.1% (n = 18) of retired and current elite athletes, respectively, was
measured physically using a watch with Global Positioning System (Garmin forerunner, 910X).
Macronutrient Intake and Energy Balance Study: In this study, twenty (male = 16 and female
= 4) junior long-distance athletes participated. The athletes were attending an eight-week training
in the camp where they were living in and training in and around Tirunesh Dibaba National
Athletics Training Centre (TDNATC) located at an altitude of 2500m (7°57′N latitude and
39°7′E longitude). The study used the three-day direct dietary record method. Nude body weight
measurements were taken before and after the three assessment days.
All food measurements were carried out when the three meals were served: breakfast (8:00 –
9:00am), lunch (12:00 am – 1:00pm), and dinner (6:00 – 7:00pm). All the measurements were
taken and recorded by the principal investigator, together with the head coach of the athletes,
using a digital weighing scale readable to 1 gram (Salter Housewares LTD, England) and the
dietary analysis of each individual athlete, including the total energy intake, and the energy
contribution and gram values for carbohydrate, fat and protein from the consumed foods was
performed using the nutritional software package Nutritics (v3.7, University Edition).
Training type, intensity and duration, as well as external load, including distance, time covered
and speed of the training were recorded in a daily training diary over the three consecutive days.
Total energy expenditure of each study participant was calculated from basal metabolic rate
(BMR) using the Schofield equation (1985) and the physical activity ratio (PAR), and physical
activity level (PAL).
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Altitude Training Study: A total of 20 (male = 16 and female = 4) junior long distance athletes
lived and trained in and around the Athletes Tirunesh Dibaba National Athletics Training Centre
were recruited for the study. The study applied the balanced, randomised, experimental design.
Before the athletes were randomly assigned to the live high - train high (LH-TH) control (n = 10
) and live high - train high train low (LH-THTL) experimental (n = 10 ) groups, they were tested
on a 5km track race at baseline (end of four pre-experimental weeks) and then assigned equally
into the two groups based on their 5km performance (time) and gender. The study lasted for a
continuous eight weeks where all the athletes lived in every day of the week, and trained light
and moderate intensity sessions at an altitude of 2500m a.s.l. four times per week. In addition,
the LH-TH and LH-THTL groups trained separately at 2500m and 1470m a.s.l. in high intensity
sessions two days per week, respectively. During the study time, different haematological,
autonomic, neuromuscular, subjective training monitor and five kilometre performance time trial
tests were conducted.
Resting haematological tests were conducted three times (baseline, week four and week eight).
Sample blood was drawn from a cubital vein under standard conditions (off-training days,
between 08:30 and 09:30 a.m. before breakfast and after a 10 minute rest period in a sitting
position) in the haematology laboratory of the College of Health Sciences of Arsi University,
Ethiopia at the specified time for complete blood count ( CBC) analysis. Like the haematological
tests, three consecutive vagal related heart rate measurements (heart rate variability and one- and
two-minute heart rate recovery measurements) were taken at baseline, week 4 and week 8. The
heart rate variability measurements were taken early in the morning, before the athletes left for
training, in their bedrooms (before leaving their beds). The one- and two-minute heart rate
recovery tests were taken as soon as the three 5km time trials were completed at baseline, week 4
and week 8. Along with the CBC and vagal-related heart rate measurements, five consecutive
neuromuscular fitness tests (at baseline, week 2, week 4, week 6 and week 8) using the common
vertical jump tests (counter movement (CMJ) and squat jump (SJ) test) were conducted after 10
hours of light intensity training. For a total of 47 training sessions, subjective training load
responses were collected using a session rating of perceived exertion (session-RPE) methods
within 30 minutes after the end of the day’s workout. At baseline, week four and week eight
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three 5km endurance performance tests were conducted on a 400m standardized synthetic track
under standard conditions (at 2500m a.s.l. and between 07:00 – 08:00 a.m.).
Results
Demographic Characteristics Study: Although the demographic characteristics study identified
significant difference between the three groups in the age at which formal training started (p <
0.001), no significant difference was identified between the groups (p > 0.05) regarding the
altitudes where the athletes were born and raised. Moreover, the study reported no significant
difference in the daily distance covered to and from school between the three groups during their
primary education (p > 0.05) but not during their secondary education (p < 0.05). The study also
revealed that there were significant regional distribution differences in the three groups (p =
0.002) where 81.3% of retired athletes and 55% of academy junior athletes were from central
Ethiopia. There was also no significant difference (p = 0.05) between the three groups in the
mode of transportation used to cover the daily distance to and from school. In addition to the
above findings, this study also found no statistically significant difference in the types of major
out-of-school activities between the three groups of athletes during their childhoods (p > 0.05).
Macronutrient Intake and Energy Balance Study: There was a significant difference between the
mean total energy intake (14593±895KJ.day-1
) and mean total energy expenditure (13423± 1134
KJ.day-1
, p < 0.001) during the three days’ dietary assessment. Moreover, the daily total energy
intake (EI) and energy expenditure (EE) throughout the three days for all subjects were also
compared in the same way as the total EI and EE. In comparison to the daily energy expenditure,
on day one there was a mismatch between EI (15682 ± 1599 KJ.day-1
) and EE (12823 ±
1397KJ.day-1
, p = 0.000), and a positive energy balance was calculated. On day two there was no
substantial difference between daily EI (14368 ± 1516KJ.day-1
) and EE (13688± 1618 KJ.day-1
,
p = 0.146). Similarly, there was also no significant difference between the EI
(13728±412KJ.day-1
) and EE (13757± 1390KJ.day-1
, p = 0.919) on day three. This study also
confirmed no significant differences in the daily energy expenditure between the three days (p =
0.091). As compared to fat and protein, it appears that CHOs were the major energy source
consumed during the three days. The overall proportion of the energy derived from the foods
revealed that CHO provided 65.7% (±11.7 %); protein 18.7% (±6.9 %) and fat 15.4% (±4.9 %).
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When the overall proportions of energy intake (KJ) derived from the three macronutrients were
analysed on a daily basis, there were statistically significant differences in CHO, protein and fat
consumption across the three days, (p < 0.001). Moreover, substantial differences were identified
in the day-to-day fat (p < 0.001) and protein (p < 0.001) consumption during the three dietary
assessment days.
Altitude Training Study
Haematological Study: No statistically significant difference in RBC count was observed
between the LH - TH and LH - THTL study groups following eight weeks of endurance training
(∆0.05; CL ±0.029; p = 0.741; ES = 0.12). After eight weeks of endurance training no significant
difference was observed in the haemoglobin concentration (p = 0.926), but substantially declined
from baseline to week eight in both groups (Experimental: ∆-0.48; CL±0.46; p = 0.040; ES = -
0.35 and control: ∆-0.51; CL± 0.46; p = 0.030; ES = -0.37). This study also identified no
substantial difference in haematocrit value between the two study groups following eight weeks
of endurance training (∆0.2; CL±1.9; p = 0.832; ES = 0.06).
Vagal-Related Heart Rate Response: The resting HRV (RMSSD) measurements revealed no
meaningful differences between the LH-TH and LH - THTL groups (∆-0.18; CL±0.43; p =
0.407; ES = -0.29) from baseline to week eight in the experimental (∆0.05; CL±0.31; p = 0.761;
ES = 0.08) and control (∆0.22; CL±0.31; p = 0.145; ES = 0.37) groups; although the changes in
both groups were positive. The difference between the experimental and control groups,
however, was negative and small (∆-0.29). The regression analysis also revealed no significant
differences, both in the one-minute (∆4.4; CL±10.8; p = 0.413; ES = 0.47) and two-minute postexercise heart rate recovery (∆3.1; CL±10.4; p = 0.550; ES = 0.31), between the experimental
and control groups.
Neuromuscular Fitness/Fatigue Response: The CMJ test results revealed no significant
difference between the two study groups following eight weeks of endurance training (∆0.5;
CL±4.8; p = 0.829; ES = 0.06), although meaningful changes were identified both in the
experimental (∆8.3; CL ±3.4; p = 0.001; ES = 0.92) and control (∆7.8; CL ±3.4; p = 0.001; ES =
0.86) groups from baseline to week eight. Significant changes in squat jump ability were
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observed, both in the experimental (∆4.8; CL±2.8; p = 0.001; ES = 0.69) and control (∆2.9;
CL±2.8; p = 0.039; ES = 0.42) groups, following eight weeks of endurance training; but not
between the groups (∆1.8; CL±3.9; p = 0.353; ES = 0.26). This study also confirmed no
significant difference between the two study groups in the eccentric utilisation ratio following
eight weeks of endurance training (∆-0.05; CL±0.16; p = 0.511; ES = -0.39).
Training Load Response: The results of the analysis identified significant differences between
the groups, and for all weekly training load responses of all training sessions, i.e., light, moderate
and high-intensity training sessions (p = 0.019) and high intensity training sessions (p = 0.000).
However, no substantial difference was identified between groups (p = 0.133) in the weekly load
responses to the light and moderate intensity training sessions. Based on the results of the least
significant difference, post-hoc meaningful differences were identified between the groups in
their weekly load response to the total intensity training at week seven and eight; as well as at
weeks one, five, seven and eight for the high intensity training sessions. Out of the 47 training
sessions, light intensity sessions (< 4 RPE, less than the first ventilatory threshold) made up
87.2% of sessions in the experimental group and 68.1% in the control group, while 12.8%
(Experimental group) and 31.9% (Control group) of the training sessions were completed at RPE
> 4 < 7 RPE (between first and second ventilatory threshold).
Five Kilometre Endurance Performance: After eight weeks of endurance training no significant
difference in the 5km endurance performance was identified between the LH-TH and LH-THTL
study groups (∆-12; CL ±25s; p = 0.335). Even though times for the 5km decreased significantly
in the experimental group (∆-19; CL±18s; p = 0.037) from baseline to week eight, performance
in the control group did not improve significantly (∆-7; CL ±18s; p = 0.440).
Conclusions
Demographic Characteristic Study: Significant difference was observed between the three
groups in the age at which formal training started. However, no significant differences were
identified between the three groups in the altitudes where the Ethiopian long-distance athletes
were born and raised, the daily distance travelled to and from school, the mode of transportation
and the major out-of-school activities during their childhood. Thus, the findings of this study
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confirmed that the 20 junior athletes who were involved in the study shared common
demographic characteristics with the retired and current elite Ethiopian long-distance athletes.
Macronutrient Intake and Energy Balance Study: In line with the previous studies conducted on
Kenyan and Ethiopian endurance athletes, the young long-distance Ethiopian athletes met the
recommended daily macronutrient intake for carbohydrates and protein for endurance athletes.
However, the study also identified that the athletes’ dietary fat consumption was below the
recommended amount for endurance athletes. Moreover, based on the three-day dietary
assessment results, the young Ethiopian endurance athletes were found to be in a state of positive
energy balance one week before their first major competition of the year (albeit during the
preparation phase of their yearly training plan).
Altitude Study: The overall results of the current altitude study revealed that in most of the study
variables (i.e., haematological, autonomic, neuromuscular, and endurance performance), except
the subjective based training load response, statistically insignificant results were identified
between the two study groups. However, when the results of the altitude study variables across
time (baseline to week eight) were examined, athletes in the LH-THTL experimental group
showed better progress in neuromuscular and lower training load responses which were
accompanied with significant five kilometer endurance performance change; and lower or
similar progress in haematological and autonomic regulation responses as compared with the
LH-TH control group. It is noted that the ultimate purpose of any type of altitude training is
enhancing the running performance while minimizing athlete’s susceptibility to injury. Taking
these core concepts of athletic training and the physiological and performance changes of the
current study in to consideration, the LH-THTL altitude training model was potentially the
preferred optimal altitude training model to further enhance the past and existing long-distance
performance of Ethiopian endurance athletes although further comprehensive studies are
required to confirm the results.
Future Directions
In order to exhaustively investigate optimal altitude training models that better enhance the longdistance performance of athletes’ native to high altitude, more comprehensive, similar studies
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should be designed. Moreover, to achieve stronger results, further studies should be conducted
using larger sample sizes with balanced gender proportions, along with more subjective and
objective training monitoring methods. Furthermore, future studies should consider additional
altitude training models, be conducted over longer periods and during different phases of the
yearly training plan (preparation, pre-competition, and competition). It is also recommended that
future studies should design endurance performance tests at different altitudes (low and high) to
enhance the local and international competition performance of Ethiopian long-distance athletes.
Description
Doctoral Degree. University of KwaZulu-Natal, Durban.