Impact of stretching on the performance and injury risk of long-distance runners

Abstract

Stretching, either prior to exercise or at the end, or both, is typically carried out by all individuals undertaking sporting activity whether they be elite or recreational athletes. The many forms of stretching available to the athlete, either passive or active, have long been thought to improve performance, decrease injury and generally be advantageous to the athlete. This review examines the current state of the literature and evaluates what athletes can and should do with respect to this controversial topic.

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Research in Sports Medicine
An International Journal
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Impact of stretching on the performance and
injury risk of long-distance runners
Claire Baxter, Lars R. Mc Naughton, Andy Sparks, Lynda Norton & David
Bentley
To cite this article: Claire Baxter, Lars R. Mc Naughton, Andy Sparks, Lynda Norton & David
Bentley (2017) Impact of stretching on the performance and injury risk of long-distance runners,
Research in Sports Medicine, 25:1, 78-90, DOI: 10.1080/15438627.2016.1258640
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Impact of stretching on the performance and injury risk of
long-distance runners
Claire Baxter
a
, Lars R. Mc Naughton
b
, Andy Sparks
b
, Lynda Norton
a
and David Bentley
a
a
School of Health Science, Flinders University, Adelaide, South Australia, Australia;
b
Sport and Physical
Activity, Edge Hill University, Ormskirk, United Kingdom
ABSTRACT
Stretching, either prior to exercise or at the end, or both, is
typically carried out by all individuals undertaking sporting activity
whether they be elite or recreational athletes. The many forms of
stretching available to the athlete, either passive or active, have
long been thought to improve performance, decrease injury and
generally be advantageous to the athlete. This review examines
the current state of the literature and evaluates what athletes can
and should do with respect to this controversial topic.
ARTICLE HISTORY
Received 8 May 2015
Accepted 17 August 2015
KEYWORDS
Performance; flexibility;
injury
Introduction
Stretching has long been considered an integral part of the training routine for athletes
and is used across all disciplines as a tool of preparation, performance enhancement and
injury prevention (Trehearn & Buresh, 2009). In recent years, however, it has been
suggested that the tendency to incorporate stretching into the regimes of athletes
was based not on science but assumption (Herbert, de Noronha, & Kamper, 2011;
Shrier, 2004; Thacker, Gilchrist, Stroup, & Kimsey, 2003).
Stretching performed prior to exercise (acutely) or as a long-term intervention has
traditionally been thought to improve the performance of endurance runners (Herbert &
Gabriel, 2002). However, inconsistency across the literature has suggested this is not
necessarily the case and may have different implications for various sports disciplines.
Delayed onset muscle soreness (DOMS) can occur after single bouts of high-intensity
running and/or unfamiliar activity (Herbert et al., 2011). The occurrence of DOMS can
result in fatigue, pain and reduction in performance, effects usually lasting 24–48 h
(Cheung, Hume, & Maxwell, 2003) and can be hindering for long-distance athletes.
Stretching has been considered to influence the incidence of DOMS in endurance
runners. Chronic overuse injuries are also frequent and devastating for long-distance
athletes. Common running-related injuries include medial tibial stress syndrome, plantar
fasciitis, achilles tendonitis, stress fractures and various knee-related injuries (Gallo,
Plakke, & Silvis, 2012). Stretching has been considered a tool for reducing the risk of
CONTACT Lars R. Mc Naughton Lars.McNaughton@edgehill.ac.uk Edge Hill University, St Helen’s Road,
Ormskirk L39 4QP, United Kingdom
RESEARCH IN SPORTS MEDICINE, 2017
VOL. 25, NO. 1, 78–90
http://dx.doi.org/10.1080/15438627.2016.1258640
© 2016 Informa UK Limited, trading as Taylor & Francis Group

injury for endurance athletes and is an additional reason stretching is often used by
endurance runners. This narrative review will report on the evidence available surround-
ing the effects of acute and chronic stretching in relation to its effects on performance,
DOMS and injury risk in endurance runners.
Does stretching improve flexibility?
Stretching is a broad term used to describe an array of passive and active movements used
to increase flexibility (Woods, Bishop, & Jones, 2007). Although there are various types of
stretching, this review primarily investigates static stretching. In contrast to the dynamic
movement associated with the other variations of stretching, static stretching involves
elongating a muscle to the point at which a gentle tension is felt and remaining in this
position for a given amount of time. Typically, multiple stretches are performed on a single
muscle group with a minimum of 30 s per stretch (Woods et al., 2007). Bandy and Irion
(1994) investigated the duration of static stretching and reported that 30 s is the optimal
period for static stretching and that increasing this duration provides no additional
advantage. It is largely unknown as to the optimal frequency (days per week) or dimen-
sions of stretching on improvements in range of motion of a joint. Each variation of
stretching has speculated to provide an assortment of advantages to athletes of varying
disciplines, however the literature has primarily examined the effects of static stretching as
this is the variation most commonly recommended to and performed by endurance
athletes (Shrier, 2004; Wallmann, Christensen, Perry, & Hoover, 2012). The second distinc-
tion in stretching referenced in this review is the acute or chronic nature of the activity.
Acute stretching refers to a temporary activity that is performed in a discrete capacity
immediately before exercise (Wallmann et al., 2012). In contrast, chronic stretching is
defined as that which is performed outside of the warm-up regime as a tool of increasing
long-term flexibility (Stone, Ramsey, Kinser, & O’Bryant, 2006).
Flexibility is a recognized fitness component and is considered a result of regular stretching
practices (Shrier, 2004; Wilson et al., 2010). However, a preliminary point to the stretching
debate is whether or not stretching does in fact improve flexibility. This is a question that has
been raised to determine whether or not the dispute surrounding the relationship between
performance and injury for athletes is central to stretching or flexibility. Is flexibility the factor
that is under scrutiny or is it simply that the common stretching methods engaged by athletes
are not increasing flexibility? The research has demonstrated that when simple static stretch-
ing is executed regularly over a minimum of 6 weeks, flexibility is significantly increased
(Bandy & Irion, 1994; Thacker et al., 2003). This leads to the distinction between acute
stretching (single bout immediately before exercise) and long-term chronic stretching (per-
formed regularly and exclusive to the warm-up regime of athletes). This is an important
difference and as a result research has been conducted on both variations in relation to its
affect on performance, DOMS and chronic injury in endurance runners.
Are endurance runners flexible?
There is evidence to suggest that typically, elite endurance runners are less flexible than
their non-elite counterparts (Saunders, Pyne, Telford, & Hawley, 2004). Posthumus,
Schwellnus and Collins (2011) completed a survey that investigated the presence of
RESEARCH IN SPORTS MEDICINE 79

the gene COL5A1 in endurance runners, a gene associated with inflexibility, which
demonstrated that endurance runners who possess this gene had a considerably higher
running economy than the other athletes participating in the study. Running economy is
a recognized determinant of the performance of endurance runners and is measured by
the energy demand of a runner at a specified velocity (Nelson, Kokkonen, Eldredge,
Cornwell, & Glickman-Weiss, 2001). This gene also had a substantially greater presence
among the endurance athletes subgroup then is estimated across the general popula-
tion (Posthumus et al., 2011). It has also been postulated that hypertrophy of muscle can
reduce the range of motion of a joint and this also could contribute to the reduced
flexibility seen in endurance runners (Wilson & Flanagan, 2008). Gleim, Stachenfeld and
Nicholas (1990) conducted a study on untrained individuals and found that the partici-
pants with the lowest flexibility consistently had the most economical running styles.
These results were justified by demonstrating that the decrease in range of motion of
the transverse and frontal physiological planes led to stabilization in the pelvic region
when the foot connected with the ground. This resulted in a reduction in excessive
range of motion and therefore an increase in the energy required to stabilize muscular
activity. It was also suggested that tightness in the muscles and tendons could increase
elastic storage and therefore reduce the oxygen demand. Thacker et al. (2003) com-
mented that the likeliness of injury is also influenced and that there is an optimal
flexibility for endurance runners. The research proposes that inflexibility can be com-
pared to that of hyperflexibility when considering injury risk (Thacker et al., 2003). A base
range of flexibility will neither improve nor decrease likeliness of developing running-
related injuries; however, extreme cases outside the normal range of flexibility might be
problematic. Future research may be directed to quantifying this optimal level of
flexibility for both performance and injury risk in the endurance running population
compared to athletes of other disciplines.
Stretching and performance
Long-distance runners, considered to be athletes that participate in events 5 km or
longer, (Cosca & Navazio, 2007) are a population that are heavily influenced by the
outcome of the stretching debate (Wilson et al., 2010). The ability of endurance running
can be divided into two main subsections. Firstly, performance potential, which is
impacted by physiological parameters such as aerobic capacity (VO
2
max) and lactate
threshold (Godges, Macrae, Longdon, Tinberg, & Macrae, 1989; Joyner & Coyle, 2008;
Wilson et al., 2010). The VO
2
max represents a number of physiological aspects including
cardiac output (Spurway, Ekblom, Noakes, & Wagner, 2012), haemoglobin levels (Ferretti,
2014), blood flow and muscle oxygen extraction (Joyner & Coyle, 2008). Lactate thresh-
old is the percentage of the VO
2
max where lactic acid levels rise sharply in the blood
(Marcell, Hawkins, Tarpenning, Hyslop, & Wiswell, 2003). The higher the percentage of
the VO
2
max in which the lactate threshold occurs equates to the athletes increased
potential for performance. The second variable is efficiency, which runs parallel to
performance and varies about 30–40% among athletes (Joyner & Coyle, 2008).
Running efficiency refers to how the body composition of an athlete impacts how
effective muscles are at using available energy (Saunders et al., 2004) and is dependent
on factors such as muscle morphology, elastic elements and joint mechanics (Engeroff,
80 C. BAXTER ET AL.

Bernardi, Vogt, & Banzer, 2014). The efficiency of movement is primarily due to anato-
mical and physiological factors of the body and methods to improve it are largely
unknown (Joyner & Coyle, 2008). The efficiency variable of running ability is where
stretching practices have the potential to impact an athlete’s success (Barnes &
Kilding, 2015). This raises the question of whether acute or chronic stretching is influen-
cing running efficiency and whether it should remain an assumed aspect of training.
Running economy is a multifactorial determinant that results from a number of
metabolic, cardiorespiratory and biomechanical characteristics including VO
2
max, lac-
tate threshold and running efficiency (Barnes & Kilding, 2015). Running economy is
defined as the steady state of oxygen consumption at a given running velocity, reflect-
ing the energy demand of running at a constant submaximal speed (Allison, Bailey, &
Folland, 2008; Barnes & Kilding, 2015). It has been considered the standard measurement
for the overall competency of runners.
Over the past 20 years, the literature on stretching and performance has expanded
and argued three standpoints, some studies providing evidence that stretching
increases performance, some arguing it decreases performance, and some stating it
does not impact it at all. Running economy was the primary indicator of performance for
the studies investigating the effect of stretching on the performance of long-distance
runners (Allison et al., 2008; Barnes & Kilding, 2015; Joyner & Coyle, 2008; Saunders et al.,
2004; Wilson et al., 2010). The debate surrounding the effects of stretching surfaced after
it was suggested that acute stretching immediately before exercise had the ability to
significantly inhibit performance on short, explosive events including the leg press one
repetition max (Bacurau et al., 2009), 20 m sprint performance (Nelson, Driscoll, Landin,
Young, & Schexnayder, 2005) and vertical jump height (Young et al., 2001) due to the
physiological changes seen in the muscle and the decreased ability to store elastic
energy (Wilson et al., 2010). As performance in long-distance running events relies on
factors such as VO
2
max, lactate threshold and biomechanical factors in contrast to the
explosive, power-oriented variables seen in anaerobic activities, a number of subsequent
studies analyzed the effects of acute stretching on endurance running (Gleim et al.,
1990; Kyrolainen & Komi, 1994; Wilson et al., 2010). Although some research demon-
strated that pre-exercise stretching has the potential to reduce explosive actions (Wilson
et al., 2010), a contrasting study reported that increased flexibility meant a reduction in
musculotendinous stiffness which by enhancing the use of elastic energy was able to
improve the results of rebound bench press (Wilson, Elliott, & Wood, 1992). However,
this study (Wilson et al., 1992) is not relevant to endurance running. No additional
studies have shown that acute stretching has the ability to improve the performance
of athletes and notably no studies have reported positive effects for endurance runners.
As a result, the debate has since evolved into whether stretching decreases running
economy for endurance runners or simply does not affect it.
Acute stretching and performance
Athletes commonly use acute stretching during their warm-up regime prior to both
training and competition (Shrier, 2004). However, the majority of the literature that has
investigated acute stretching and endurance running argues that stretching causes a
decrease in running economy (Saunders et al., 2004; Shrier, 2004; Thacker et al., 2003).
RESEARCH IN SPORTS MEDICINE 81

The central idea behind this phenomenon is that stretching before an endurance event
reduces mechanical efficiency of the lower body (Kyrolainen & Komi, 1994) primarily
through the reduction of musculotendinous stiffness (Thacker et al., 2003). A musculo-
tendinous unit is defined as the contractile muscle and the attached tendinous struc-
tures (McLachlan, Murphy, Watsford, & Rees, 2006), and musculotendinous stiffness
refers specifically refers to the units ability to resist an applied change in length
(Kuitunen, Komi, & Kyrolainen, 2002). Although this stiffness has traditionally been
considered a factor that has the potential to increase the risk of injury and inhibit
athlete’s performance in the early stages of a race, it appears it is a desirable trait for
long-distance runners (Wilson & Flanagan, 2008). The reduction in mechanical efficiency
stems directly from the decrement in muscle stiffness that appears as a result of static
stretching. The specific reasoning behind why a decrease in musculotendinous stiffness
leads to reduced mechanical efficiency varied throughout the literature; however, all
reported that acute stretching before endurance-based events does not assist athletes
performance and in fact can diminish it (Craib et al., 1996; Kyrolainen & Komi, 1994;
Wilson et al., 2010). One study suggested that stiffer muscles surrounding the ankle and
knee joints causes an increase in force potentiation when transitioning from the braking
to push offphase of running (Kyrolainen & Komi, 1994) and proposed that stiffer
muscles provide the best running economy and results. Craib et al. (1996) investigated
the effect of short and rapid stretching on running economy and found that inflexibility
in the hip and calf regions were associated with improved running economy as less
energy was required for muscle stabilization. The improved running economy may be a
result of increased pelvis stability and a reduction in required muscle activation at foot
strike to maintain stability. An additional study described that acute stretching may
result in an increase in the number of motor units recruited to perform the same
amount of mechanical work that is required without stretching. Activation of a larger
number of motor units means an increase in both oxygen consumption and energy
expenditure (Wilson et al., 2010). Additionally, Gleim et al. (1990) argue that efficient
elastic energy storage and return is favoured for endurance athletes with a tighter
musculotendinous system. Furthermore, acute stretching has the ability to strain the
muscle, causing a decrease in force development, and an increase in oxygen require-
ment within the hour following the stretching regime (Shrier, 2004).
Hayes and Walker (2007) suggested that a 10-min submaximal warm-up run prior to
performance testing could reverse the reduction in active peak force and rate of force
development while retaining the improved stretch-absorbing capacity and therefore not
impact running economy. Furthermore, Allison et al. (2008) reported that changes in
neuromuscular function due to stretching were evident in participants but had no effect
on running economy. However, no studies were able to suggest that stretching imme-
diately before an endurance running event could improve running economy (Shrier,
2004;Thacker et al., 2003). A small number of studies that investigated the performance
of isolated muscle groups demonstrated that stretching before performance testing can
increase the strength of that muscle group at specific isokinetic degrees (Akagi &
Takahashi, 2014; Godges et al., 1989), however these results did not provide evidence
to suggest that the same results could be applied to endurance running (Worrell, Smith,
& Winegardner, 1994). Furthermore, when Godges et al. (1989) conducted a follow-up
82 C. BAXTER ET AL.

study on a larger population, it was reported that no effect on running economy was
seen (Bonacci, Chapman, Blanch, & Vicenzino, 2009).
In conclusion, stretching does not possess properties that warrant it a useful or
effective tool in the warm-up regime of long-distance runners. Although the data are
not entirely conclusive and the literature demonstrates some disparity, there is little to
suggest that acute stretching has properties that can enhance performance for endur-
ance athletes and in fact may have the opposite effect. This research suggests that
endurance athletes may be best reducing their warm-up routine to a low-intensity,
progressive run and removing stretching practices completely.
Chronic effects of stretching and performance
It has been argued that provided that stretching is not completed immediately before
exercise –as is generally the case for athletes engaging in chronic stretching –increased
flexibility as a result of regular stretching will not inhibit performance or decrease
running economy (Godges, MacRae, & Engelke, 1993; Nelson et al., 2001). Nelson et al.
(2001) conducted a study involving 32 participants over 10 weeks and noted that
although flexibility was significantly increased over the study duration, it did not appear
to effect running economy. The study makes specific mention that the exercise was not
performed immediately following the stretching regime and although running economy
was not reduced it also did not show improvement. There was no studies found that
reported that running economy would either improve or decline from long-term
stretching programmes. However, as previously reported, the literature does suggest
that an increased running economy has a high association with inflexibility in endurance
runners (Gleim et al., 1990; Posthumus et al., 2011; Saunders et al., 2004) As a result,
unless stretching possesses other health or performance-related benefits, it appears to
have little purpose in an endurance runner’s preparation. The research suggests that
there may be an optimal level of flexibility for running economy, in which a balance
between muscle stiffness in order to maximize elastic energy storage and return is
achieved while allowing enough movement for optimal stride length at high running
speeds (Saunders et al., 2004).
The literature suggests acute stretching regimes do not help endurance runner’s
performance, and may in fact decrease running economy. Specifically, by decreasing
musculotendinous stiffness, acute stretching reduces stability and force production, in
turn decreasing mechanical efficiency and increasing oxygen demand (Wilson &
Flanagan, 2008). Therefore, if individuals feel it necessary to include stretching in their
daily routine, it is suggested that it is not performed immediately before running.
Further research is required to clarify the effects of chronic stretching on endurance
running performance. Furthermore, the evidence on dynamic stretching is limited and
requires further examination. Although no studies were able to provide evidence that
acute stretching positively impacts performance for endurance runners the effects of
chronic stretching on endurance running performance is unknown and is an area
requiring further investigation. A notable weakness that is seen across all relevant
literature examining the relationship between stretching and performance is the lack
of explanation and are primarily speculative in nature. There are limited evidence-based
claims which describe why acute and chronic stretching affect performance.
RESEARCH IN SPORTS MEDICINE 83

Stretching and delayed onset muscle soreness
DOMS is common and debilitating for endurance runners (Cheung et al., 2003). DOMS
cancausediscomfortinthemuscleandistheleadingcauseofreducedperformance
in subsequent exercise, decreased muscle strength and range of motion (High,
Howley, & Franks, 1989). The specific cause of DOMS is unknown; however, it is
thought to be triggered by a series of biochemical changes that occur as a result
of muscle damage (Fridén, 2002). It is often seen when individuals are exposed to
high force eccentric contractions repeatedly and/or unaccustomed exercise. Running
has a significant eccentric component which has been implicated in the manifestation
of DOMS (Cheung et al., 2003). As a result, DOMS is prevalent following bouts of
high-intensity or downhill running exercise. Therefore, a reduction in the incidence of
DOMS and therefore an improvement in recovery would be such a quality to encou-
rage endurance athletes to leave stretching in their daily routine.
The use of stretching to prevent DOMS was supported by the idea that muscle
soreness was a result of unfamiliar exercise causing muscle spasm (de Vries, 1966).
Muscle spasm was thought to reduce blood flow to the muscle and conversely, stretch-
ing was thought to restore blood to the muscle, interrupting the pain–spasm–pain cycle
(Herbert et al., 2011). High et al. (1989) conducted a study that investigated the effect of
stretching on DOMS of 62 healthy participants in order to investigate these claims.
Results were compared among the individuals in the experimental (static stretching) and
control (non-stretching) conditions and the results demonstrated that there was no
significant difference between muscle soreness over the following 5 days. These findings
were supported by a number of additional studies, reporting that acute stretching does
not provide a significant impact on DOMS following exhaustive exercise (Buroker &
Schwane, 1989; Johansson, Lindström, Sundelin, & Lindström, 1999; McGlynn, Laughlin,
& Rowe, 1979; Wessel & Wan, 1994). Furthermore, Herbert and Gabriel (2002) reported
that although a small amount of improvement may be seen in DOMS following stretch-
ing, it is too insignificant to warrant athletes including it into their warm-up regime.
Herbert et al. (2011) reported that there was no evidence that suggested static or
dynamic stretching performed before or after exercise or in an acute or chronic capacity
had the ability to reduce the severity or duration of DOMS. Jamtvedt et al. (2010)
supported these claims surveying over 2,000 individuals and concluding that no varia-
tion of stretching has the ability to alter DOMS.
Similarly to the effects on performance, there is no evidence found which suggests
that stretching has the ability to reduce either the presence of DOMS or the pre-
valence of chronic injury in long-distance runners. A number of studies have inves-
tigated the relationship between stretching and the presence of DOMS following
exercise and the unanimous response is that the duration and intensity of DOMS
cannot be influenced by stretching (Dannecker, Koltyn, Riley, & Robinson, 2002;
Herbert et al., 2011). There was no evidence to suggest stretching could assist in
the reduction of DOMS across the literature for athletes of any discipline (Herbert
et al., 2011). It is recommended that athletes suffering from DOMS investigate other
prevention methods, such as massaging, icing or hot and cold therapy (Sforzo, Ankita,
&Swensen,2011;Snyderetal.,2011).
84 C. BAXTER ET AL.

Stretching and chronic injury
The bulk of the literature investigating the relationship between stretching and injury for
long-distance runners has focused on chronic, long-term, degenerative injuries –which
are seen most commonly in this population. Although competitive endurance runners
are most frequently in their 20s and 30s, the majority of participants are within the
35–50 years bracket (Cosca & Navazio, 2007). As a result, this population is at a high risk
for running-related chronic injuries such as illiotibial band friction, achilles tendinopathy
and plantar fasciitis (Cosca & Navazio, 2007; Gallo et al., 2012). Marti, Vader, Minder, and
Abelin (1988) conducted a study on over 4,000 male runners and reported that 45%
sustained an injury over a 1 year period with inflammation to the achilles tendon and
calf muscle injuries among the most common.
The majority of studies suggest that stretching has no impact of the risk of chronic
injury in endurance runners (Cosca & Navazio, 2007; Thacker et al., 2003; Witvrouw,
Mahieu, Danneels, & McNair, 2004). It has shown that long-term stretching can poten-
tially increase the compliance of the muscle–tendon unit (Toft, Espersen, Kalund,
Sinkjaer, & Hornemann, 1989) and may allow greater force production at longer muscle
lengths (McHugh & Nesse, 2008) which may be relevant to other sporting disciplines;
however, Witvrouw et al. (2004) highlight that for endurance running these potential
benefits are not clinically beneficial. When participating in a long-distance running
event, the lower limbs engage in a repetitive motion at a submaximal intensity. This
means the tendons in the legs are unlikely to require maximum energy absorption and
elastic stability to perform the exercise (Witvrouw et al., 2004). This applies to all
endurance events which include repetitive motion such as long-distance cycling and
swimming. As a result of this, the likeliness that the endurance athletes will encounter
muscle strain injuries is low in comparison to highly explosive sports which require
maximum effort out of the musculotendinous structures.
Dutch researchers (van Mechelen, Hlobil, Kemper, Voorn, & de Jongh, 1993) studied
the effect of stretching on injury over a 10-week programme and reported that stretch-
ing made no impact on the prevalence of overuse injuries. Furthermore, the study did
not report any muscle or tendon strain-related injuries supporting the idea that overuse
injuries are the most frequent for endurance runners. This also supports that although
there is potential advantages for a subset of sporting activities, due to the nature of the
injuries generally experienced by endurance runners, stretching provides no assistance
in reducing the risk of injury (McHugh & Cosgrave, 2010). Pope, Herbert, Kirwan, and
Graham (2000) conducted a study which reinforced these claims, surveying over 1,000
military recruits and concluding that stretching did not affect the prevalence of chronic
overuse injuries in their population.
Bonacci et al. (2009) have commented that although stretching has not demonstrated
any ability to reduce the risk of injury in endurance runners, it can be an important tool
in the maintenance and promotion of range of motion in hip, knee and ankle joints after
injury. An additional study investigated the effect of flexibility on vertical jump techni-
que and suggested that stretching has both advantageous and disadvantageous proper-
ties depending on the activities that individuals are participating in and what the athlete
is trying to achieve (Hunter & Marshall, 2002). This highlights that the relationship
between the effects of stretching and sporting activities generally is not clear and
RESEARCH IN SPORTS MEDICINE 85

some athletes may benefit from incorporating chronic stretching into their routine from
an injury risk standpoint.
When investigating the relationship between stretching and chronic injury, the
literature shows a higher degree of discrepancy. Stretching may possess qualities that
will help reduce the likeliness of muscle and tendon strain injuries; however, this is
unrelated to the subset of injuries most experienced by endurance runners (McHugh &
Cosgrave, 2010). As a result it can be concluded that stretching provides no significant
assistance in the reduction of chronic overuse injuries and therefore is not a useful injury
preventative strategy for endurance athletes. Further research is required to determine
whether stretching has the ability to reduce the prevalence of muscle strain injuries and
should remain incorporated into the warm-up regime of athletes of different areas.
Practical implications
The available research suggests neither acute nor chronic static stretching has clinically
beneficial effects for endurance runners on performance, incidence of DOMS or to
prevent injury. Therefore, other strategies could be used to assist a runner with pre-
paration and recovery. Bazyler et al. (2011) conducted a study to investigate the benefit
of a submaximal warm-up for endurance performance and found no significant
improvements in performance. Similarly, investigations involving dynamic stretching
techniques have shown little evidence to suggest it provides any advantage to endur-
ance athletes (Dalleck, Janot, & Reyment, 2007). However, the research outside of static
stretching is limited (Dalleck et al., 2007) and is an area requiring further research. From
the current literature, it can be concluded that stretching is an ineffective way of altering
performance or injury risk and endurance athletes are advised to direct their efforts to
other strategies. In terms of pre-exercise activities, this may include a progressive warm-
up prior to exercise which incorporates graded intensity. Athletes are also recom-
mended to individualize their training programmes in order to promote performance
responses and reduce injury risk. Aside from the improvement of athletes lactate thresh-
old and VO
2
max, supplementary efforts such as resistance training (Dean, Lamb, Ceri, &
Twist, 2013) have reported to assist in the performance of endurance runners and may
be a useful incorporation into the training schedule of athletes. Endurance runners
experiencing common overuse injuries are advised to treat each injury individually
and acknowledge that risk factors such as extensive mileage can impact the risk of
developing a chronic injury in the lower limbs (Warden, Davis, & Fredericson, 2014).
Therefore, progressive and planned training in combination with over recovery mod-
alities may be the most effective way to reduce injury risk and promote recovery during
period of high running volume. Cross and interval training may be techniques used to
reduce weekly mileage and the likeliness of overuse injuries (Millet, Vleck, & Bentley,
2011).
Conclusion
In conclusion, the literature suggests that stretching poses no significant advantage to
endurance runners. Acute stretching can reduce running economy and performance for
up to an hour by diminishing the musculotendinous stiffness and elastic energy
86 C. BAXTER ET AL.

potential. Chronic stretching additionally appears to have no advantageous effects. In
regards to DOMS, it has been reported consistently in the literature that stretching
cannot reduce its longevity or intensity. In relation to injury risk, stretching shows little
significance for endurance runners to chronic injury. Endurance athletes are at high risk
of overuse injuries such as illiotibial band syndrome, stress fractures and plantar fasciitis,
and the literature suggests that stretching cannot reduce the prevalence of these
injuries. It appears stretching may hold significance for certain exercise disciplines;
however, it can be concluded that it holds no advantage for endurance runners and is
not the solution to improving performance or reducing injury prevalence.
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCID
Lars R. Mc Naughton http://orcid.org/0000-0002-3743-3171
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