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Running injuries in novice runners enrolled in different training
interventions: a pilot randomized controlled trial
J. Baltich
1
, C. A. Emery
2,3
, J. L. Whittaker
4
, B. M. Nigg
1
1
Human Performance Laboratory (HPL), Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada,
2
Sport
Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada,
3
The Alberta
Children’s Hospital Research Institute for Child and Maternal Health, Cumming School of Medicine, University of Calgary,
Calgary, Alberta, Canada,
4
Department of Physical Therapy, Faculty of Rehabilitation Medicine, Glen Sather Sports Medicine
Clinic, University of Alberta, Edmonton, Alberta, Canada
Corresponding author: Jennifer Baltich, Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500
University Drive NW, Calgary, Alberta, Canada T2N 1N4. Tel: +403 220 5142, Fax: +403 282 7637, E-mail: jbaltich@
ucalgary.ca
Accepted for publication 5 July 2016
The purpose of this trial was to evaluate injury risk in
novice runners participating in different strength training
interventions. This was a pilot randomized controlled trial.
Novice runners (n=129, 18–60 years old, <2 years recent
running experience) were block randomized to one of three
groups: a “resistance” strength training group, a
“functional” strength training group, or a stretching
“control” group. The primary outcome was running related
injury. The number of participants with complaints and the
injury rate (IR =no. injuries/1000 running hours) were
quantified for each intervention group. For the first
8 weeks, participants were instructed to complete their
training intervention three to five times a week. The
remaining 4 months was a maintenance period. Trial
registration: NCT01900262. A total of 52 of the 129
(40%) novice runners experienced at least one running
related injury: 21 in the functional strength training
program, 16 in the resistance strength training program
and 15 in the control stretching program. Injury rates did
not differ between study groups [IR =32.9 (95% CI 20.8,
49.3) in the functional group, IR =31.6 (95% CI 18.4,
50.5) in the resistance group, and IR =26.7 (95% CI 15.2,
43.2)] in the control group. Although this was a pilot
assessment, home-based strength training did not appear to
alter injury rates compared to stretching. Future studies
should consider methods to minimize participant drop out
to allow for the assessment of injury risk. Injury risk in
novice runners based on this pilot study will inform the
development of future larger studies investigating the
impact of injury prevention interventions.
Scientific evidence for the benefits of aerobic exercise
has continued to grow over the years. A recent meta-
analysis demonstrates that regular running is associ-
ated with reduced body mass, resting heart rate and
triglycerides, and increased maximal oxygen uptake
and high density lipoprotein cholesterol (Hespanhol
Junior et al., 2015). Despite the enormous health
benefits, the majority of runners will experience a
running related injury (Hespanhol Junior et al.,
2015; Videbæk et al., 2015). Individuals that are new
to running (novice runners) have been shown to have
a higher incidence of running-related injuries than
experienced runners (Videbæk et al., 2015). In addi-
tion to the short-term reduction in activity associated
with an injury, some runners will lose motivation to
run once exposed to an injury, possibly leading to
long-term inactivity (Koplan et al., 1995; Lohman-
der et al., 2004). This may be particularly true for
new runners who are returning to exercise after a
period of inactivity and have yet to form consistent
training habits involving physical activity. Preven-
tion of running injuries for novice runners is impor-
tant to enable these individuals to remain active and
avoid comorbidities associated with inactivity, such
as heart disease and obesity.
Interventions aimed at preventing running related
injuries have aimed to alter risk factors associated
with injury (van Mechelen et al., 1993; Buist et al.,
2008). Previous randomized controlled trials (RCT)
and quasi-experimental studies have demonstrated
that running injury prevention interventions that
reduced weekly running mileage or included a
stretching warm up did not reduce the risk of injury
in novice runners (van Mechelen et al., 1993; Buist
et al., 2008). Another theory is that reduced muscu-
lar strength limits the ability to control movements
at the joints, resulting in increased strain on the soft
tissues and ultimately leading to injury. Some injury
1
Scand J Med Sci Sports 2016: :–
doi: 10.1111/sms.12743
ª2016 John Wiley & Sons A/S.
Published by John Wiley & Sons Ltd
prevention interventions have focused on increasing
the strength of the hip musculature for a “top down”
approach to reduce movements at the joints and the
associated injury risk (Hott et al., 2015; Palmer
et al., 2015). However, knowledge can be gained
from evaluating other strengthening interventions
that may alter running mechanics and reduce injury
risk. One form of strengthening that may be relevant
is a “bottom up” approach focusing on the ankle
musculature (Tiberio, 1987; Feltner & Macrae, 1994;
Hollman et al., 2005; Nigg et al., 2006). Another
approach may be to step away from isolated forms
of joint muscle strengthening and incorporating
functional sport-specific movement forms of strength
training (Cates & Cavanaugh, 2009). Both resistance
training at the ankle joint and functional sport-speci-
fic movement strength training, or neuromuscular
training, have been shown to increase strength
(Tropp & Askling, 1988; Feltner & Macrae, 1994;
Heitkamp et al., 2001) and reduce lower extremity
joint movements (Feltner & Macrae, 1994; Myer
et al., 2006). However, the influence of these two dif-
ferent types of strength training on running injury
incidence in novice runners is currently unknown.
Injury surveillance in novice runners requires
detailed attention to the follow-up period and injury
definition. For example, differences in injury rates
between novice runners and experienced runners
were found only with longer follow-up periods
(1 year) as opposed to shorter follow-up periods (8–
12 weeks) (Kluitenberg et al., 2015a). With respect
to injury definition, an injury is typically defined
based on a medical attention, full time loss from
activity or a reduction in training volume injury defi-
nition (Bahr, 2009). The definition of injury can have
a significant influence on the reported injury rates in
a group of runners (Kluitenberg et al., 2015b). It is
therefore important to consider the type of runners
who are being evaluated when choosing the appro-
priate injury definition. For example, the injury pro-
portions reported with the medical attention
definition is low (0.9–15.6% on average) across all
runners except for ultra-marathon runners (65.6%
on average) (Kluitenberg et al., 2015a). Addition-
ally, overuse injuries may be under-reported, as it is
possible that individuals will continue to train with-
out seeking medical attention, despite the presence of
pain from an overuse injury (Junge & Dvorak, 2000;
Bahr, 2009; Clarsen et al., 2012). In summary, the
evaluation of an injury prevention intervention for
novice runners requires follow-up for a sufficient
duration (6 months–1 year) using an injury surveil-
lance methodology that includes overuse symptoms
(Clarsen et al., 2012).
Currently, there is little knowledge about the effi-
cacy of either resistance strength training at the ankle
or a functional sport-specific movement form of
strength training to reduce the incidence of injury in
novice runners. Therefore, the objectives of this pilot
RCT are to compare injury incidence rates in healthy
adult novice runners participating in an 8-week resis-
tance ankle strengthening program, an 8-week func-
tional sport-specific movement strength training
program or a stretching control program. In this
pilot study, it was hypothesized that the risk of injury
in the resistance strength training group and the
functional strength training group would be lower
than the control stretching group.
Materials and methods
Study design & participant population
The current study was part of the Calgary Strength for Novice
Runners Study, an RCT conducted in the Faculty of Kinesiol-
ogy at the University of Calgary. The study design and proce-
dures have described in detail previously (Baltich et al., 2014).
All participants provided written informed consent in accor-
dance with the University of Calgary’s policy on research
using human participants. This RCT has been registered with
ClinicalTrials.gov (NCT01900262) and approval for this
research project was obtained from the University of Cal-
gary’s Conjoint Health Research Ethics Board (Ethics ID:
REB13-0153). Novice recreational runners were recruited for
this study as they have been shown to have a higher risk of
running related injuries (Macera et al., 1989; Rolf, 1995;
Tonoli et al., 2010; Genin et al., 2011; Videbæk et al., 2015).
Inclusion criteria included the following: (1) less than 2 years
of recent weekly running exposure, (2) 18–60 years of age, (3)
no pain or injury within 3 months of testing, (4) running is the
primary form of exercise and (5) no weekly resistance band or
functional strength training in the previous year. Participants
were recruited through use of posters, university website
advertisements, social media advertisements, and word of
mouth. Participants were randomly assigned to one of three
training groups: a resistance strength training group focusing
on strengthening the ankle joint musculature, a functional
sport-specific movement strength training group, or stretching
control group. An unpredictable randomized allocation
sequence was generated using a random allocation scheme
(one block) with a 1:1:1 allocation ratio between the three
groups. Randomization was not stratified by age or gender.
After participants provided written informed consent and
completed their baseline assessment, they sequentially drew a
numbered, opaque, sealed envelope, and signed the back
before opening the envelope to determine their group
allocation.
Interventions
All exercise interventions were home based and have been
described previously (Table 1) (Baltich et al., 2014). A warm-
up routine consisting of aerobic activity, static and dynamic
stretching was taught to participants in all three groups. For
the stretching control group, participants completed this
warm up for 25-min with no additional training. Stretching
was chosen as a control intervention as it has previously been
shown to have no protective effect in reducing the risk of run-
ning related injury (van Mechelen et al., 1993; Lauersen et al.,
2014). The resistance strength training group and the func-
tional strength training group were asked to complete this
warm up for 5 min in addition to 20 min of group-specific
exercises. For the resistance strength training group,
2
Baltich et al.
Table 1. Training routines for the control stretching, functional strength training, and resistance strength training groups. Adapted from (Baltich et al., 2014)
Stretching control Functional strength training Resistance
strength training
Aerobic
warm up
Static
stretch
Dynamic
stretch
Stretch Lunge Squat Hop Single
leg
standing
Single
leg
standing
Jumps Stretch Resistance
band
Isometric
against
wall
Weeks
1,2
5 min:
side to
side shuttle,
high knee
skipping,
light
running
10 min:
groin,
hamstring,
quadriceps,
calves
10 min:
buttock
kicks,
leg swings
5 min:
aerobic warm
up, static &
dynamic
stretch
10 Reps:
flat ground,
forward &
backward
10 Reps:
flat
ground,
two feet
5 Reps: flat
ground, two
foot box
hop
5930 s:
flat
ground,
eyes
open
5930 s:
flat
ground,
eyes
closed
20 Reps:
flat
ground,
side to
side
5 min:
aerobic
warm up,
static &
dynamic
stretch
Red, 4
sets
of 10
395s
Weeks
3,4
5 min:
side to side
shuttle,
high knee
skipping,
light
running
10 min:
groin,
hamstring,
quadriceps,
calves
10 min:
buttock
kicks,
leg
swings
5 min:
aerobic
warm up,
static &
dynamic
stretch
5 Reps: flat
ground,
lunge
around the
clock
10 Reps:
BOSU ball,
two feet
5 Reps: flat
ground,
one foot
box hop
5930 s:
flat
ground,
trunk lean,
eyes open
5930 s:
flat ground,
trunk lean,
eyes
closed
5 Reps:
flat
ground,
star form,
alter feet
5 min:
aerobic
warm
up, static
& dynamic
stretch
Green, 4
sets
of 10
595s
Weeks
5,6
5 min: side to
side shuttle,
high knee
skipping,
light
running
10 min:
groin,
hamstring,
quadriceps,
calves
10 min:
buttock
kicks,
leg swings
5 min:
aerobic
warm up,
static &
dynamic
stretch
10 Reps:
BOSU ball,
forward &
backward
10 Reps:
Flat ground,
one foot
10 BOSU
ball, two
foot hop
5930 s:
BOSU ball,
eyes open
5930 s:
BOSU
ball eyes
closed
3 reps: flat
ground,
star form,
one foot
5 min:
aerobic
warm
up, static
&
dynamic
stretch
Blue, 4
sets
of 10
3910 s
Weeks
7,8
5 min: side
to side
shuttle,
high knee
skipping,
light
running
10 min: groin,
hamstring,
quadriceps,
calves
10 min:
buttock
kicks,
leg swings
5 min:
aerobic
warm up,
static &
dynamic
stretch
20 Reps:
BOSU ball,
forward &
backward
10 Reps:
BOSU ball,
one foot
10 BOSU
ball, one
foot hop
5930 s: BOSU
ball, trunk lean,
eyes open
5930 s:
BOSU ball,
trunk lean,
eyes closed
3 reps:
flat ground,
star form,
one foot
5 min:
aerobic
warm up,
static &
dynamic
stretch
Black,
4
sets
of 10
5910 s
3
Strength training and running injuries
participants completed a training program with elastic bands
that increased in stiffness every 2 weeks for the first 8 weeks
of the study. Participants in the functional strength training
group were provided with a BOSU
ball (Hedstrom Fitness,
Ashland, Ohio, USA) and asked to complete lunges, squats,
hops, single leg standing and jumps. These exercises increased
in difficulty every 2 weeks for the 8 week training period. Par-
ticipants met in person with the study coordinator every
2 weeks to receive their new equipment and exercises. The 6-
month follow-up period was split into a training period
(8 weeks) and a maintenance period (16 weeks). All partici-
pants were instructed to complete their respective training
protocol three to five times per week in addition to running at
least once a week for the 8 week training period. Following
the 8 week training period, participants were asked to com-
plete their respective training protocol twice a week in addi-
tion to running at least once a week for the remaining
4 month maintenance period. Each participant received an
instructional videotape as well as one-page summary sheets
outlining their exercises. Participants were asked to report
their training and running exposure (minutes) on a weekly
online form. Participants were not aware of the content of the
other interventions.
Outcome measures
All participants completed a baseline questionnaire including
information about running experience (weeks of exposure, fre-
quency per week, average weekly mileage, average training
session duration), preferred running surface (e.g. grass,
asphalt, trail, etc.), number of running shoes, frequency of
replacing running footwear, motivation for running and his-
tory of previous injuries.
The primary outcome of this study was running related
injury. A running related injury was defined as any muscu-
loskeletal complaint of the lower extremity or lower back
caused as a result of running that resulted in a restriction in
running (running distance, duration) for at least 1 week (Buist
et al., 2008). Participants were asked to only report injuries
that they believed were a direct result of running. Injuries that
they did not believe were caused from running were not
reported. If a participant suffered from an injury that resulted
in time loss from training for at least 1 week, they were
instructed to contact the study coordinator to set up a visit
with a physiotherapist at the University of Calgary. At this
visit, the physiotherapist completed a clinical assessment.
Non-running related injuries that were sustained in the
6 month study period were not included in the analyses.
Running exposure, training exposure and physical com-
plaints related to running were self-reported online on a
weekly basis through StudyTRAX, a web-based Electronic
Data Capture system. Running logs included information
regarding the number of running minutes and location (e.g.
grass, track, treadmill, etc.) for each day of the week. Training
exposure included the number of training sessions completed
each week. Physical complaints were tracked using an overuse
injury questionnaire (Clarsen et al., 2013). This questionnaire
asked four questions, including the existence of a physical
complaint that hindered running training, how much this
complaint hindered weekly training distance and duration,
and the extent of the pain associated with the physical com-
plaint. Participants were specifically asked if they had any
complaints at their ankle, knee, or hip. An ‘other’ category
was provided for any physical complaints in other regions
(e.g. lower leg, lower back, upper leg, foot, etc.). Anatomical
location of the injury was self-reported and was not confirmed
with a manikin or any other form of imagery. Messages were
sent by email 1 day before the weekly due date to remind par-
ticipants to complete the online form the following day. A
reminder email was automatically sent if the form was not
completed within 2 days of the due date. If runners did not
complete the online form within 1 week of the initial email,
they were contacted directly by phone to complete the form
either online or over the phone. To reduce the chance of recall
bias, participants were provided with a paper log identical to
the online format to record their daily running and training
exposure on a weekly basis.
Statistical analyses
This study was an exploratory investigation evaluating the
injury incidence rate in novice runners enrolled in different
exercise interventions. An exploratory power analysis was
completed for the expected injury incidence proportions for
this study based on previous studies investigating running
injuries in untrained runners enrolled in running training pro-
grams (Bovens et al., 1989; Taunton et al., 2003). If the inter-
vention groups should lead to a 50% reduction in the injury
incidence and assuming the control group has an injury inci-
dence of 40% (per 100 runners), 82 subjects would be needed
in each group to achieve 80% statistical power with an
a=0.05. Due to the lack of power, the injury outcome analy-
ses for this pilot RCT was exploratory.
The injury incidence proportion (IP) was quantified as the
proportion of runners that sustained at least one running
injury during the 6-month follow-up period. The injury inci-
dence rate (IR) was estimated for each group as the number of
running related injuries per 1000 h of running exposure. Mul-
tiple injuries were taken into account in the calculation of the
IR. The running hours until the time of injury as well as fol-
lowing the injury were also taken into account for the calcula-
tion of the IR. The number of physical complaints in each
body region (lower extremity and lower back) was recorded.
Weekly severity of each physical complaint was rated on a
scale from 0 to 100 (0 =no complaint, 100 =full time loss
with severe pain) as described previously (Clarsen et al., 2013)
(Fig. 1). The week the physical complaint first appeared, as
well as the average weekly severity associated with that com-
plaint, was recorded for all injuries related to running. The
amount of running reduction (minor, moderate, major, full
time loss) was also recorded for all injuries from the physical
complaint questionnaire. If a participant complained of dis-
comfort at multiple anatomical regions, the physical com-
plaint with the highest severity score was identified as the
most severe running related injury.
Results
Population
For the 8 week exercise intervention period, nine
runners (21%) in the functional strength training
group, 15 runners (35%) in the resistance strength
training group and 19 runners (44%) in the stretch-
ing control group dropped out prior to the comple-
tion of the 8-week training period (Fig. 2). An
additional 11 runners (20 total, 47%) from the func-
tional strength training group, four runners (19 total,
44%) from the resistance strength training group
and three runners (22 total, 51%) from the stretching
control group dropped out prior to the full 6 month
completion date (Fig. 2). Baseline anthropometric
4
Baltich et al.
and running experience characteristics for the partic-
ipants that completed the 6 -month follow-up period
as well as the participants that dropped out of the
study are presented in Table 2. Baseline characteris-
tics of those that dropped out of the study and those
that remained in the study appeared similar between
the three training groups.
Adherence training intervention
In the functional strength training group, 22 partici-
pants (51%) completed at least four sessions per
week, 15 (35%) completed two to three sessions per
week and six (14%) completed less than two sessions
per week. For the resistance strength training group,
28 participants (65%) completed at least four ses-
sions per week, 12 (28%) completed two to three ses-
sions per week and three (7%) completed less than
two sessions per week. For the control group, 24 par-
ticipants (56%) completed at least four sessions per
week, 13 (30%) completed two to three sessions per
week and six (14%) completed less than two sessions
per week.
Running related injuries
Of the 129 allocated novice runners in this study, 52
sustained a running-related injury. For the resistance
training group, the 16 participants (37%) reported a
running related injury. For the functional strength
training group, 21 participants (48%) reported a run-
ning related injury, and for the control stretching
group 15 participants (35%) reported a running
related injury. For the participants that reported a
running related injury, 15 (71%) runners in the
functional strength training group, 11 (68%) runners
in the resistance strength training group and 7 (46%)
runners in the stretching control group had reported
a previous lower extremity injury at some point in
their life. Baseline anthropometric measures as well
as running exposure characteristics for the injured
and non-injured participants in each training group
are presented in Table 3.
Four participants of 52 (8%) reported more than
one running related injury: two functional strength
training group participants, one resistance strength
training group participant and one stretching control
group participants. The resistance strength training
group ran a mean of 12.5 h (total =538.5 h) during
the 6-month follow-up period, while runners in the
functional strength training ran a mean of 16.3 h (to-
tal =699.4 h) and the stretching control group ran a
mean of 14 h (total =600.3 h). The running IR was
31.6 injuries/1000 running hours (95% CI; 18.4,
50.5) for the resistance strength training group, 32.9
(95% CI; 20.8, 49.3) for the functional strength
training group, and 26.7 (95% CI; 15.2, 43.2) for the
control group. Weekly severity scores for the most
severe injury of each participant who reported a run-
ning related injury can be seen in Fig. 3.
Of the 96 participants that completed at least three
training sessions on average per week as instructed
(per protocol analysis: resistance =36, func-
tional =32, control =28), 43 participants (45%)
reported at least one running-related injury. For the
resistance training group, 14 participants (36%)
reported at least one running-related injury. For the
functional training group, 16 participants (50%)
reported at least one related injury and for the
stretching group 12 participants (43%) reported at
Fig. 1. (a) Example of an injury questionnaire for ankle complaints and (b) exemplary weekly severity score at the ankle joint
for one participant.
5
Strength training and running injuries
least one running related injury. One participant in
the resistance training group and one participant in
the functional training group reported two running
related injuries. The resistance training group ran a
total of 506 h while the functional training ran a
total of 672 h and the control group ran a total of
Fig. 2. Flow of participants through the study protocol.
6
Baltich et al.
536 h. The running IR was 27.7/1000 running hours
(95% CI; 15.1, 46.5) for the resistance training
group, 25.3 (95% CI; 14.7, 40.5) for the functional
training group and 22.4 (95% CI; 11.6, 39.2) for the
control group.
Knee injuries made up the majority of running
related injuries across all three intervention groups
(46%, 26 of the 56 reported injuries). The ankle was
the next most commonly injured location (20%, 11
of the 56 reported injuries), followed by the foot
(11%, 6 of the 56 reported injuries). Table 4 details
the number of running related injuries, the mean
severity score, and the prevalence of time loss injuries
at each anatomical location for each group. The
mean weekly severity of running related injuries was
similar across the three intervention groups [100
Table 2. Baseline anthropometric and running history characteristics
Characteristic Functional strength training Resistance strength training Stretching control
Completed
(n=23, 53%)
Drop out
(n=20, 47%)
Completed
(n=24, 56%)
Drop out
(n=19, 44%)
Completed
(n=21, 49%)
Drop out
(n=22, 51%)
Ge nder (nfemale, %) 21 (91) 13 (65) 16 (67) 17 (89) 17 (81) 19 (86)
Age (years; median, range) 33 (22, 54) 32 (20, 57) 30 (18, 50) 37 (19, 50) 31 (18, 59) 34 (18, 50)
Height (cm; median, range) 165 (148, 182) 169 (156, 182) 167 (155, 189) 163 (156, 181) 166 (150, 181) 165 (153, 182)
Mass (kg; median, range) 66 (49, 99) 78 (56, 102) 75 (51, 150) 74 (57, 95) 70 (56, 110) 79 (49, 106)
Running experience
(weeks; median, range)
8 (0, 104) 6 (0, 104) 1 (0, 64) 0 (0, 32) 10 (0, 104) 3 (0, 77)
Frequency of runs per week
(median, range)
2 (0, 4) 2 (0, 4) 1 (0, 4) 0 (0, 4) 2 (0, 5) 1 (0, 3)
Weekly distance
(km; median, range)
8 (0, 25) 4 (0, 15) 4 (0, 18) 0 (0, 25) 10 (0, 35) 2 (0, 20)
Training session duration
(minutes; median, range)
30 (0, 60) 20 (0, 60) 18 (0, 40) 0 (0, 30) 25 (0, 45) 20 (0, 45)
Previous injuries (n, %) 12 (52) 13 (65) 14 (58) 11 (58) 10 (48) 11 (50)
Primary training surface (n,%)
Pavement 9 (39) 4 (20) 8 (33) 6 (32) 4 (19) 11 (50)
Trail 1 (4) 2 (10) 0 0 0 0
Treadmill 10 (44) 11 (55) 12 (50) 9 (47) 15 (71) 10 (45)
Indoor Track 3 (13) 3 (15) 4 (17) 4 (21) 2 (10) 1 (5)
Pairs of running footwear (n,%)
12 11 (48) 11 (55) 14 (58) 13 (68) 12 (57) 16 (73)
3 10 (43) 7 (35) 10 (42) 6 (32) 8 (38) 5 (22)
>3 0 1 (5) 0 0 0 1 (5)
Frequency of replacing footwear (n,%)
6–12 months 15 (65) 10 (50) 10 (42) 11 (58) 12 (57) 16 (73)
13–24 months 5 (22) 6 (30) 10 (42) 4 (21) 5 (24) 2 (9)
>24 months 3 (13) 4 (20) 4 (16) 4 (21) 4 (19) 4 (18)
Table 3. Running exposure and baseline anthropometric characteristics for the injured and non-injured participants in each training group
Characteristic Functional strength training Resistance strength training Stretching control
Injured,
n=21, 49%
Non-injured,
n=22, 51%
Injured,
n=16, 37%
Non-injured,
n=27, 63%
Injured,
n=15, 35%
Non-injured,
n=28, 65%
Gender (nfemale, %) 19 (90) 15 (68) 12 (75) 21 (78) 11 (73) 25 (89)
Age (years; median, range) 33 (22, 57) 33 (20, 54) 32 (18, 50) 31 (19, 50) 36 (18, 54) 33 (18, 59)
Height (cm; median, range) 166 (156, 182) 166 (148, 182) 166 (159, 189) 167 (155, 184) 162 (150, 181) 167 (154, 182)
Mass (kg; median, range) 70 (49, 102) 73 (50, 98) 75 (58, 131) 74 (51, 150) 82 (56, 110) 74 (49, 106)
Baseline running experience
(weeks; median, range)
12 (0, 104) 3 (0, 104) 4 (0, 24) 0 (0, 64) 10 (0, 520 6 (0, 104)
Previous injuries (n, %) 15 (71) 10 (45) 11 (68) 13 (48) 7 (460 14 (50)
Total running exposure
(hours; median, range)
10.1 (1.4, 47.5) 18.1 (0, 50.3) 14.6 (0.7, 49.1) 8.1 (0, 31.2) 12.9 (0.6, 51.9) 6.9 (0, 58.9)
Weekly running exposure
(minutes; median, range)
55 (32, 119) 54 (0, 132) 51 (25, 131) 51 (0, 140) 85 (28, 130) 45 (0, 297)
Total running exposure
before injury
(hours; median, range)
3 (1, 38) NA 5 (1, 15) NA 4 (1, 15) NA
First appearance of injury
(week; median, range)
5 (1, 21) NA 5 (1, 18) NA 4 (1, 9) NA
7
Strength training and running injuries
point scale: median, range; functional strength train-
ing 43.0 (31.0, 92.0); resistance strength training 37.7
(31.0, 84.4); stretching control 37 (31.0, 78.1)]. Of the
56 running related injuries, 10 required moderate or
major reductions in running duration and/or dis-
tance: three participants in the functional strength
training group, three participants in the resistance
strength training group and four participants in the
stretching control group. Twelve participants
required full time loss from running for at least
1 week: seven participants in the functional strength
training group, four in the resistance strength train-
ing group and one in the stretching control group.
Time loss injuries that underwent clinical assessment
by a physiotherapists included the following: Foot –
midfoot sprain, peroneus longus tendinitis (2), plan-
tar fasciitis, bony projection irritation; Ankle -
Achilles tendinopathy; Knee –tibiofibular ligament
sprain, anterior cruciate ligament sprain, patellofe-
moral pain syndrome (2), medial knee joint line pain;
Upper leg –hamstring muscle strain.
The number of new running related injuries and
the total running exposure hours for each month of
the 6-month follow-up period are presented in
Table 5. All training groups experienced the major-
ity of running related injuries during the 8-week
training period. For the functional strength training
group, 83% (19 of 23) of the running related injuries
first appeared during the 8-week training period. For
the resistance training group, 65% (11 of 17) of the
running related injuries first appeared during the
8 week training period and 88% (14 of 16) of the
running related injuries in the stretching control
group appeared during the first 8 weeks of the study.
Discussion
The purpose of this RCT was to explore the inci-
dence of injury in novice runners enrolled in a resis-
tance strength training program, a functional
strength training program, or a stretching control
program. It was speculated that this exploratory
study would provide useful information for future
RCTs regarding the risk of injury and dropout rates
accompanying home based exercise interventions
geared towards novice runners. This discussion will
focus on four main findings from this study: (1)
There was no difference between study groups on
running injury rates; (2) injury rates in the current
study are relatively high, highlighting the utility of
using a weekly overuse injury surveillance question-
naire; (3) injury rates were higher during the 8 week
Fig. 3. Weekly severity scores for the most severe injury reported by each participant during the 6-month follow-up period.
Severity scores ranged from zero (no complaint) to 100 (time loss with severe pain). Each gray and white box represents the
severity score for a single participant as a function of time. Participants who completed the entire 6-month follow-up period
are shaded while participants who dropped out are represented as lines.
8
Baltich et al.
training period compared to the 4 month mainte-
nance period for all three groups.
While the sample size was small, leading to the risk
of type II error, the injury rates were similar between
the three training groups for the 6-month tracking
period. Due to the lack of power, this study cannot
definitively determine the effectiveness of either
strengthening intervention. The results from this
study can be used to accurately power a larger RCT
to effectively evaluate the influence of these training
interventions on injury risk. The sample size for this
RCT was determined based on the assumption of a
20% drop out rate. The dropout rates for the full 6-
month follow-up period were approximately 50%
across all three training interventions. Previous stud-
ies reported dropout rates between 10% and 20%
(van Mechelen et al., 1993; Buist et al., 2008; Bre-
deweg et al., 2012). However, previous intervention
studies recruited runners that were currently enrolled
in a start-to-run program (Buist et al., 2008; Bre-
deweg et al., 2012). The runners in the current study
were not a part of any organized running group.
Therefore, they may have lost motivation to run
more easily without the incentive of an organized
running group. Future RCTs evaluating a home-
based training intervention for runners that are not
involved in an organized running group should
develop strategies to reduce the risk of participant
dropout. This may include more contact with study
coordinators or organized group training and run-
ning sessions. If this support is not available, future
studies should adjust their sample size calculation for
a larger dropout rate.
The higher than average loss to follow-up rates in
the current study may be due to a variety of reasons,
including the lack of belief that the given training
intervention will help, the ease of the training pro-
gram or the lack of enjoyment that comes from par-
ticipating in the training. The lack of enjoyment for
the stretching intervention may be of particular
interest. The stretching exercises did not change over
the course of the 8 week training period, whereas the
resistance and functional strength training exercises
became progressively more difficult every 2 weeks.
This monotonous structure may not have been stim-
ulating enough to maintain the interest of the partici-
pant. Future research that incorporates a stretching
control group should consider changing the stretch-
ing exercises every 2 weeks to try to increase the
interest of the participant. An objective
Table 4. Anatomical distribution of running related injuries
Functional strength training Resistance strength training Stretching control
Injury
rate
(/1000 h)
Time loss
(n)
Average weekly
severity score
(median, range)
Injury
rate
(/1000 h)
Time
loss (n)
Average weekly
severity score
(median, range)
Injury
rate
(/1000 h)
Time
loss (n)
Average weekly
severity score
(median, range)
Total 32.9 7 43 (31, 92) 31.6 4 38 (31, 84) 26.7 1 37 (31, 78)
Foot 5.7 4 69 (61, 77) 1.9 1 68.5 1.7 0 37
Ankle 4.3 0 46 (37, 60) 7.4 1 47 (31, 84) 6.6 0 35 (31, 40)
Lower leg 2.8 0 47 (36, 58) 0 0 0 1.7 0 44
Knee 15.7 3 49 (31, 92) 16.7 2 38 (31, 62) 10.0 0 38 (31, 60)
Upper leg 1.4 0 46 1.9 0 35 1.7 1 78.1
Hip 1.4 0 34 1.9 0 37 1.7 0 44.2
Lower back 1.4 0 37 1.9 0 37 3.3 0 37 (37, 37)
Table 5. Frequency of new running related injuries, running exposure hours and injury incidence rate (no. injuries per 1000 h of exposure) for each
month of the 6-month follow-up
Functional strength training Resistance strength training Stretching control
Running
related injuries
(n)
Running
exposure
(h)
Injury
rate
(n/1000 h)
Running
related
injuries (n)
Running
exposure (h)
Injury
rate
(n/1000 h)
Running
related
injuries (n)
Running
exposure
(h)
Injury
rate
(n/1000 h)
Weeks 1–4 10 165.3 60.4 7 140.8 49.7 10 149.1 67.1
Weeks 5–8 9 141.9 63.4 4 102.9 38.9 4 106.4 37.6
Weeks 9–12 2 92.9 21.5 1 86.5 11.6 2 93.7 21.4
Weeks 13–16 0 105.8 0.0 3 65.7 45.6 0 83.8 0.0
Weeks 17–20 0 85.2 0.0 1 76.8 13.0 0 93.4 0.0
Weeks 21–24 2 108.5 19.4 1 65.8 15.2 0 74.0 0.0
Total 23 699.4 30.0 17 538.5 29.7 16 600.3 25.0
9
Strength training and running injuries
questionnaire provided to dropout participants
would also elucidate more details regarding their
choice to leave the study.
For the current study, running injury rates ranged
between 25 and 30 injuries per 1000 h of running
exposure. Previous studies have reported injury rates
in novice runners ranging from 8.9 (95% CI 7.6,
10.3) to 33.0 (95% CI 27.0, 40.0) injuries per 1000 h
of running exposure (Bovens et al., 1989; Buist et al.,
2008). A recent meta-analysis estimated running
injury rates for novice runners to be 17.8 (95% CI
16.7, 19.1) injuries per 1000 h of running exposure
based on past studies (Videbæk et al., 2015). The
injury rates for the current study are at the upper
end of the range of previously reported injury rates
for novice runners. This finding may partially be a
result of the nature of the injury definition and the
overuse injury questionnaire used to identify running
injuries. Only 12 participants (23%) that sustained a
running related injury in the current study required
time loss from running. The remaining participants
reported reductions in running exposure due to their
injury, but did not have to stop running all together.
Therefore, a large portion of running related com-
plaints would not have been captured if a time loss
injury definition had been used to track novice run-
ners. Future studies investigating injury incidence in
novice runners should consider using an overuse
injury questionnaire to capture a more inclusive rep-
resentation of the injury burden.
The current findings also support the potential
need for a pre-conditioning period when training
novice runners. The results from this pilot investiga-
tion indicate that all three training groups had the
highest incidence of injury during the first 8 weeks of
the study during the training period compared to the
4 month maintenance period after the training. It
should be noted that this could be a result of report-
ing bias since running injuries were self-reported and
only the time loss injuries were clinically evaluated
by a physiotherapist. When considering the injury
location, complaints at the foot had some of the
highest average severity scores. A tissue will posi-
tively remodel and strengthen in response to an
external load, as long as enough recovery time is pro-
vided (Kjaer, 2004). If the recovery time is not suffi-
cient or the external load is too high, an overuse
injury may occur (Hreljac, 2004). As novice runners
tend to be inactive prior to commencing a regular
running routine (Buist et al., 2010), the combination
of regular running in addition to exercise training
may have overloaded the tissues in the foot. It may
have been more beneficial to begin the exercise train-
ing intervention prior to commencing a regular run-
ning routine. However, a previous RCT found that
participation in a preconditioning program incorpo-
rating walking and hopping exercises prior to
commencing a running program did not influence
the incidence of injury in a group of novice runners
(Bredeweg et al., 2012). This preconditioning pro-
gram, however, was only 4 weeks in duration. There-
fore, it could be that a longer preconditioning period
(8 weeks) prior to commencement of a running pro-
gram may be more beneficial than starting both the
running routine and the exercise intervention at the
same time.
One of the strengths of this investigation includes
the rigorous RCT methodology. In addition, the
inclusion of running exposure on a weekly basis
informed the estimation of injury rates rather than
depending purely on injury incidence proportions.
This is also the first study to evaluate injury risk
associated with home-based strength training inter-
ventions for novice runners. Certain limitations exist
for this study. First and foremost the small sample
size is a limitation. While this was intended to be a
pilot RCT for injury risk evaluation, the high drop-
out rate was unanticipated and further reduced the
sample size. A larger sample would have allowed for
the initial goal of using a more comprehensive statis-
tical analysis (multivariate regression analysis),
which could have included controlling for potential
confounders such as previous injury and running
experience at baseline (Baltich et al., 2014). If the
intervention groups should lead to a 50% reduction
in the injury incidence and assuming the control
group has an injury incidence of 40% (per 100 run-
ners), 82 subjects would be needed in each group in
order to achieve 80% statistical power with an
a=0.05. Accounting for a 50% drop out rate would
require 164 participants in each group for future lar-
ger scale RCTs. The loss to follow-up may have also
resulted in selection bias. Another limitation is the
limited staff resources available for this RCT. The
use of more research staff may have allowed for
more frequent direct contact with the participants to
increase motivation and training participation for
new runners. Additionally, only the time loss injuries
were clinically evaluated by a physiotherapist. All
other physical complaints were self-reported by par-
ticipants. This cohort of runners was also primarily
female, making the generalizability to males difficult.
Finally, a longer follow-up period of up to one year
may have been informative regarding long-term
injury incidence.
Perspectives
The results of this pilot study suggest that the injury
incidence proportion and injury rate are similar for
novice runners enrolled in a resistance strength train-
ing program, a functional strength training program,
or a stretching program. Dropout rates of approxi-
mately 50% in the current study are higher than
10
Baltich et al.
previously reported dropout rates for participants
enrolled in a supervised running group. Of the 52
participants who reported running related injuries,
only 12 injuries lead to time loss from running, sup-
porting the use of an overuse questionnaire to report
all injuries rather than a time loss definition. The
majority of running related injuries were reported
during the first 8 weeks of the 6-month follow-up
period. The purpose of this pilot RCT was to gain
knowledge for a future larger-scale RCT evaluating
home-based strength training for novice runner
injury prevention. The results of this study bring into
the question the practicality of executing a larger-
scale study with the same design. The high drop-out
rates in combination with the high yet similar injury
rates between groups would promote adjustments to
the study design. Future research should consider
implementing the strength training interventions as a
pre-conditioning program prior to commencing a
regular running routine. Additionally, different
methods to promote participant retention should be
considered for novice runners enrolled in a home-
based exercise intervention. Alternatively, the use of
supervised training may increase adherence to the
training, reduce drop-out rates, and improve the
potential for injury reduction. Future results from
this RCT will include the influence of training on
strength, running mechanics and balance in novice
runners.
Acknowledgements
Jennifer Baltich was supported through PhD stu-
dentships from the Canadian Institutes of Health
Research (Vanier Canada) and Alberta Innovates
Health Solutions. Carolyn Emery is supported
through a Chair in Pediatric Rehabilitation (Alberta
Children’s Hospital Foundation). We would like to
thank all participants for their time and dedication
to this study.
Key words: Athletic injury, novice, prevention,
strength training.
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