Keywords
age - athletics - video - biomechanics - ageing - javelin - throwing
Introduction
Javelin throwing was already part of the pentathlon in the first modern Olympic Games
in Athens in 1896 and became a separate event in the Olympic Games in 1908. Unlike
other throwing events, not only arm, upper body and core strength are required, but
also speed and agility [12]
[19]. Indeed, javelin throwing consists of an approach run and the subsequent release
of the javelin. The speed of the approach run (a run-up and two or three cross-over
steps) is an important factor for the success of a javelin throw. The approach run
is followed by the release phase (one-legged and two-legged support phase) and braking
phase [15]. The second-last cross-over step, the impulse step, allows the centre of mass to
be above the rear leg to prepare for a long acceleration path and the strike. A high
velocity at release and an angle of release (the direction of pull) between 32° and
36° have been associated with good results [12]. Further important factors are the elbow angle, which should ideally be 180°, and
the angle of attitude (the angle between the longitudinal axis of the javelin and
the horizontal line at moment of release; see [Fig. 1]). The difference between the angle of attitude and the angle of release is called
the angle of attack [15] and should be as low as possible to enhance the energy transfer to the javelin [12].
Fig. 1 Angles of interest during javelin throwing: α: angle of release, β: angle of attitude, γ: angle of attack, δ: elbow angle just before the pull.
In recent years, master athletics, competitions for any athlete older than 35 years,
has gained growing popularity, including participation in international javelin throwing
competitions. In many other events, an accelerated decline in performance was shown
after the age of 70 [3]
[5]
[11] that is at least partly attributable to an ageing-related reduction in pulmonary
function [6]
[7], loss of muscle strength and reduction in tendon stiffness [1]
[10], and loss of motor units [8]
[16]. It is not known, however, whether such an accelerated ageing-related decline in
older age also occurs in the performance of javelin throwing, because performance
is not only determined by physiological factors, but also, as discussed above, by
technique.
Although many studies have been conducted on javelin-throwing techniques and biomechanics
in young and well-performing athletes [2]
[12]
[14]
[19]
[20], as far as we know there are no studies in older javelin throwers. Master javelin
throwers may well change their technique to compensate for deficits in muscle strength,
speed and agility, and to minimise pain during some movements. Ageing-related changes
in throwing technique within the older master athlete population may thus cause larger
decrements in performance than expected from physiological changes alone. Understanding
their throwing behaviour and biomechanical differences from young athletes is not
only important for training and competition purposes, but also interesting for the
understanding of movement and musculoskeletal and neuronal changes during the ageing
process.
The aim of the present study was to assess ageing-related changes in javelin-throwing
performance using the performances of master javelin throwers in three master athletics
competitions. In addition, we sought to determine to what extent throwing technique
contributes to performance in 69+-year-old male master javelin throwers and whether the technique shows ageing-related
changes in this population of athletes. It was hypothesized that javelin-throwing
performance shows an accelerated decline after the age of 69 years.
Materials and Methods
Ethical approval was obtained from RWTH Aachen University Hospital IRB (reference
number EK 178/17, date of approval: August 3, 2017). Ethical standards were according
to international standards as required by the journal [9]. Informed consent was not needed, as data were collected during three master javelin-throwing
competitions and anonymised before analysis, according to the declaration of Helsinki.
To maintain anonymity of athletes, details on the place and date of competitions are
not reported.
Age groups
In master athletics, participants are allocated to 5-year age groups. For example,
all male athletes between 80 and 84 years of age are in age group M80, and a 78-year-old
male athlete is allocated to age group M75. The mass of the javelin decreases with
age. While the javelin for men up to 49 years weighs 800 g, its weight drops each
decade, where men of 70–79 years of age use a 500- g javelin, and athletes 80 years
and older throw a 400-g javelin. For the first part of the study, we retrieved the
current world records for men in each age group [21] and recorded the performance of all male javelin-throwers who participated in the
three competitions. Age-graded performance (AGP) was reported as a percentage of the
world record at the corresponding age. We also calculated the predicted performance
for each of the 27 athletes, using a regression equation of performance vs. age in
the study population of 27 male 69+-year-old javelin throwers. Five of these athletes participated in age class M70,
eight in M75, eleven in M80 and three in M85.
Inclusion and exclusion criteria
The inclusion criterion was participation in the javelin-throw competition in age
class M70 or older. To participate in the competitions, athletes did not have to qualify,
but they had to be registered with a track and field club. Three to six throws of
27 male 69+-year-old javelin throwers were filmed for later video analysis as described below.
The best attempt of each athlete was selected for analysis. In some cases, analysis
of the video images of the best throw was impossible when people standing or walking
between the athlete and camera obstructed the field of view. In those cases, the next
best attempt was selected. Weather conditions were fine in each of the three competitions
without rain or significant wind.
Video analysis
A Canon EOS 60D camera with a Canon EF 75-300 mm zoom lens was used for filming (full
HD 1920×1080 px, 25 fps). The camera was positioned as illustrated in [Fig. 2]. Screenshots were made of the video files and angles were calculated. The number
of steps was counted. When an athlete walked before running, only the steps of the
run were counted. When an athlete only walked, the total number of steps was counted.
[Fig. 1] shows which angles were measured and used for statistical analysis. Effects of wind
were ignored. The angle of attack was calculated as: angle of attack=angle of attitude
– angle of release.
Fig. 2 Runway and camera position seen from above. The camera was positioned at a 90° angle
to the arc line ending the runway. The sector covers a 28.96° angle; the runway is
4 m wide and at least 30 m long.
Statistical analysis
SPSS (v. 23 IBM) was used for analysis. Linear regression was performed for javelin
world-records vs. age, and for the actual performance or AGP in three athletic events
vs. age for the 35- to 69-year-olds and 69+-year-old athletes, separately. A stepwise linear regression was done to assess to
what extent performance (actual performance (in m), AGP and percentage of predicted
performance) was determined by age, angle of attack, angle of release, angle of attitude,
elbow angle and steps. These factors were fed into the model only if they correlated
with performance at P<0.05. The adjusted R2 is presented. Significance was assumed at P<0.05. An excel file with the data can
be found in the Figshare online data repository at the following URL: https://figshare.com/articles/supplement_xlsx/5661676
Results
[Fig. 3a] shows a linear decline (R2=0.97; P<0.001) in javelin-throwing world-records. In our population, the ageing-related
decline in distance thrown was accelerated after age 69 years ([Fig. 3b]), and the AGP decreased with age ([Fig. 3c]). The latter indicates that younger athletes on average performed better than older
athletes in comparison to their age group’s world record.
Fig. 3 a Javelin-throwing world-records (numbers taken from [21] on August 8th, 2017) correlate negatively with age (R2=0.97; P<0.001). b Javelin-throwing performance in athletes participating in the three competitions.
The ageing-related decline is faster after the age of 69 years (slope younger athletes:
–0.32 m·y−1; after 69 years: –1.25 m·y−1). c Age-graded performance in the participating athletes.
Stepwise linear regression showed age as the most important predictor of actual performance
in the athletes 70 years and older (R2=0.68; P<0.001), facilitated by elbow angle (R2 increased to 0.76) and angle of attack (R2=0.82). To exclude the influence of age, we repeated the analysis for the age-graded
performance (AGP). It appeared that elbow angle was the most important determinant
of AGP (R2=0.34; P≤0.001), with additional contributions of age (R2=0.49) and angle of attack (R2=0.60). As age still appeared as a factor, we repeated the analysis with the predicted
performance derived from the regression equation of distance thrown vs. age in the
older athletes. In that case, elbow angle was the most important determinant of performance
(R2=0.212; P=0.009) facilitated by angle of attack (R2=0.341).
Neither the number of steps, nor the angles of attitude, release and attack, nor elbow
angle showed a significant correlation with age ([Fig. 4]).
Fig. 4 The elbow angle, angle of attitude, angle of attack and angle of release in male
69+-year-old javelin throwers.
Discussion
In the present study, 27 master athletes, age 69 years and older, were filmed during
javelin-throw championships and their throwing technique was analyzed. The main observation
is an accelerated ageing-related decline in javelin throwing performance after the
age of 69 years, both in terms of distance thrown and age-graded performance. Although
performance was to some extent determined by technique, by the elbow angle before
the pull and angle of attack, there was no ageing-related change in technique in the
69+-year-old male javelin throwers. The accelerated decline in javelin throwing performance
is therefore most likely related to accelerated ageing-related declines in physiological
function, such as muscle strength, and/or prevention of pain during the event.
Javelin-throwing performance
While javelin-throwing world-records show a linear decrease with age [21], the ageing-related decline in the athletes who participated in the three competitions
in 2017 showed an accelerated decline after the age of 69 years. This is in line with
the accelerated decline observed around the same age in sprint time and endurance
performance in cross-sectional [11]
[17] and longitudinal studies [3]
[5]. In addition, the age-graded performance of javelin throwers decreased after the
age of 69 years, but little before that. As an explanation of this phenomenon, the
world records in the older age groups are much more influenced by individuals who
have the optimal genetic constitution to perform well than in younger age groups.
Alternatively, pain and/or other physical limitations may affect athletes in varying
degrees. Finally, after retirement, some people seem to develop an increased interest
in athletics who were previously not or little involved. Compared to athletes who
continuously participated, those people would probably perform less, as they neither
have the experience and routine, nor maintained their training throughout life. This
group of athletes is an interesting subject for future studies.
Throwing techniques in older athletes compared to those reported in younger athletes
The angle of attitude is known to be an important factor for success in javelin throwing
[12]
[19]
[20] and ranges between 36° and 48° [3] in young elite athletes. In the present study, the average attitude angle of athletes
in the 69+ age group was lower than average (32.5°). A similar situation applies to the angle
of release, which has been reported between 33° and 38° in 20- to 35-year-old athletes
[15], but was only 29.6° in our 69+-year-old athlete population. Because a high angle of release results in a high flight
path when the javelin is thrown at high velocity, the inability to release the javelin
at high velocity may thus be compensated by a lower angle of release. In older athletes
who cannot release the javelin at a high enough velocity, a high angle of release
will cause the javelin to land with the rear end first, making the throw invalid.
Another relevant factor might be the angle of the elbow before starting to pull and
release. The average angle of the elbow just before the pull was 118.3°, although
ideally it should be 180°. A lower angle of the elbow will lead to an elevation of
the javelin and a flatter release angle may thus be an additional compensation for
the inability to release the javelin at a high velocity. In addition, older athletes
may not be able to keep their arms straight due to chronic damage to, or pain in,
their shoulder and elbow joints [18], muscle weakness, lack of training in throwing techniques and/or, as discussed above
for the release angle, an adaptation in throwing technique to prevent invalid throws.
The angle of attack should be as small as possible and reflects how well the impulse
is transferred to the javelin [12]
[15]. Indeed, in 12 Swiss decathletes and two world-class specialists the better throwers
had a lower angle of attack [12], and elite javelin throwers had smaller angles [15] that were occasionally even negative [20]. Angles of attack of the master athletes in the present study (3.5° +/– 12.4°) were
also occasionally negative and in the range seen in younger athletes, suggesting the
angle of attack per se does not explain lower performance of the older compared to
younger javelin throwers.
The performance of javelin throwing has been reported to be positively related to
the athlete’s running speed [12]
[15]
[20]. In elite athletes, the length of the approach run varies between 26 and 36 meters
and running speed is between 6.0 to 7.3 m/s in men [15]. This distance was much shorter for our older athletes, and some even threw the
javelin from a standing position, missing the impulse from the body to thrust the
javelin forward.
The above observations do suggest that part of the lower performance in 69+-year-old compared to 30- to 69-year-old master javelin throwers can be attributed
to a difference in technique. The positive relationship between elbow angle and angle
of attack with performance within the 69+ -year-old male javelin throwers does not explain an accelerated decline in performance
because there was no correlation with age for these parameters. Most likely, the accelerated
decline is attributable to a loss of muscle power, which in leg muscles has been shown
to result in a decreased 6-min walking distance and timed up-and-go performance only
if it decreased below a certain threshold level [13]
[18].
Study limitation
Javelin throwing is a three-dimensional and complex movement [4], and the analysis of the present study was performed only in two dimensions. However,
the camera had a high resolution with exceptional video quality and was positioned
perpendicular to the direction of throw, maximising the visibility of the angles in
the plane of interest. Another limitation is the purely male cohort. The study is,
however, unique because 69 + -year-old javelin throwers were filmed during actual competitions.
Conclusion
In conclusion, the decline in javelin-throwing performance accelerates after the age
of 69 years. Although performance was to some extent determined by technique, and
especially the elbow angle before the pull and the angle of attack, the accelerated
ageing-related decline in 69+-year-old male javelin throwers was only marginally attributable to ageing-related
changes in technique after the age of 69 years. In explanation, we suggest the accelerated
decline in javelin throwing performance (after the age of 69) is caused by accelerated
ageing-related declines in physiological function, such as muscle strength, and/or
the prevention of pain during the event. Practical implications of the study include
1) the theory of a linear decline in performance at high age needs to be revised and
a more rapid decline is expected beyond the age of 69 years; 2) in older master athletes,
javelin throwing performance is determined by physiological function and to some extent
by technique; and 3) the javelin throwing technique employed is independent of age.
Future investigations
To answer the question of whether the accelerated decline beyond age 69 is real or
caused by increased participation after retirement more research is required. Larger
groups of athletes and the individual athlete’s longitudinal development should be
analysed. Research should be extended to a variety of sports and disciplines to allow
a more thorough view on performance declines, because each sport and discipline covers
a different spectrum of abilities such as speed, power, agility, and others.
