ArticlePDF Available

Exercise-Induced Muscle Damage and Recovery in Young and Middle-Aged Males with Different Resistance Training Experience

Authors:

Abstract and Figures

This study compared the time course of recovery after squatting exercise in trained young (YG; n= 9; age 22.3 ± 1.7 years) and trained (MT; n= 9; 39.9 ± 6.2 years) and untrained (MU; n= 9; age 44.4 ± 6.3 years) middle-aged males. Before and at 24 and 72 hours after 10x10 squats at 60% one-repetition maximum (1RM), participants provided measurements of perceived muscle soreness (VAS), creatine kinase (CK), maximal voluntary contraction (MVC), voluntary activation (VA) and resting doublet force of the knee extensors and squatting peak power at 20 and 80% 1RM. When compared to the YG males, the MT experienced likely and very likely moderate decrements in MVC, resting doublet force and peak power at 20 and 80% 1RM accompanied by unclear differences in VAS, CK and VA after squatting exercise. MU males, compared to MT, experienced greater alterations in peak power at 20 and 80% 1RM and VAS. Alterations in CK, MVC, VA and resting doublet force were unclear at all time-points between the middle-aged groups. Middle-aged experienced greater symptoms of muscle damage and an impaired recovery profile than young resistance trained males. Moreover, regardless of resistance training experience, middle-aged males are subject to similar symptoms after muscle-damaging lower-body exercise.
Content may be subject to copyright.
sports
Article
Exercise-Induced Muscle Damage and Recovery in
Young and Middle-Aged Males with Dierent
Resistance Training Experience
John F. T. Fernandes 1,2,*, Kevin L. Lamb 2and Craig Twist 2
1Sport, Health and Well-being Arena, Hartpury University, Hartpury GL19 3BE, UK
2Department of Sport and Exercise Science, University of Chester, Chester CH1 4BJ, UK;
k.lamb@chester.ac.uk (K.L.L.); c.twist@chester.ac.uk (C.T.)
*Correspondence: jfmtfernandes@hotmail.co.uk
Received: 3 April 2019; Accepted: 23 May 2019; Published: 29 May 2019


Abstract:
This study compared the time course of recovery after a squatting exercise in trained young
(YG; n=9; age 22.3
±
1.7 years) and trained (MT; n=9; 39.9
±
6.2 years) and untrained (MU; n=
9; age 44.4
±
6.3 years) middle-aged males. Before and at 24 and 72 h after 10
×
10 squats at 60%
one-repetition maximum (1RM), participants provided measurements of perceived muscle soreness
(VAS), creatine kinase (CK), maximal voluntary contraction (MVC), voluntary activation (VA), and
resting doublet force of the knee extensors and squatting peak power at 20% and 80% 1RM. When
compared to the YG males, the MT experienced likely and very likely moderate decrements in MVC,
resting doublet force, and peak power at 20% and 80% 1RM accompanied by unclear dierences
in VAS, CK, and VA after the squatting exercise. MU males, compared to MT, experienced greater
alterations in peak power at 20% and 80% 1RM and VAS. Alterations in CK, MVC, VA, and resting
doublet force were unclear at all time-points between the middle-aged groups. Middle-aged males
experienced greater symptoms of muscle damage and an impaired recovery profile than young
resistance trained males. Moreover, regardless of resistance training experience, middle-aged males
are subject to similar symptoms after muscle-damaging lower-body exercise.
Keywords: squatting; ageing; muscle damage
1. Introduction
The number of middle-aged (i.e., 30 to 59 years old) people in the U.K. is increasing [
1
]. Alongside
this is a growing number of middle-aged athletes, many of whom want to maintain or improve their
athletic performances despite the natural age-related declines [
2
]. Specifically, these impairments are
because of losses in muscle mass [
3
] and strength and power [
3
,
4
], of which, the lower-body undergoes
the greatest losses [
3
5
]. Importantly, resistance training can provide a potent method of ameliorating
these age-associated losses in muscle mass, strength, and power [6].
When used acutely, resistance exercise can cause exercise-induced muscle damage (EIMD; [
6
]),
for which the mechanisms have been discussed extensively before (see [
7
]). EIMD symptoms include
increases in muscle soreness, intramuscular enzymes in the blood serum, and plasma, and, of most
importance to the athlete, an impaired muscle function [
8
]. Importantly, changes in muscle function
provide the best indication of EIMD [
7
,
8
]. Although highly individualised [
9
], these symptoms typically
peak between 24 and 48 h after the initial bout and are recovered by seven days [
7
]. A muscle’s
susceptibility to damage might also be aected (reduced) in subsequent bouts where prior eccentric
exercise has occurred [
10
,
11
]. Two studies have noted that this protection from eccentric exercise is less
pronounced (~29% in MVC) in untrained older, compared to younger, men [
12
,
13
], which suggests
Sports 2019,7, 132; doi:10.3390/sports7060132 www.mdpi.com/journal/sports
Sports 2019,7, 132 2 of 13
that older resistance-trained men might exhibit symptoms of EIMD that are not dissimilar to their
untrained counterparts.
Studies examining the recovery of older and younger untrained adults after muscle-damaging
exercise are equivocal. Some studies have reported greater symptoms of EIMD in younger, compared
to older, males [
14
,
15
], while others have observed greater EIMD in older (~59 to 66 years), compared
to younger, males (~23 years) (17). Moreover, a number of studies have reported no dierence in
symptoms of EIMD after exercise for young populations (~19 years), compared to older populations
(~48 to 76 years) [
6
,
16
19
]. One confounding factor in the current literature might be the physical
activity and resistance training status of the participants. For example, when controlling for physical
activity, Buford et al. [
18
] noted that recovery from muscle-damaging unilateral plantar flexion was
similar among young (~23 years) and older (~76 years) adults. Despite the eectiveness of resistance
training in combating the age-associated losses, only one study has investigated the EIMD response
in older resistance trained males. Like Buford et al. [
18
], Gordon and colleagues [
16
] observed
no dierences in indirect markers of EIMD between recreationally trained young (~22 years) and
middle-aged (~47 years) males after damaging knee extensor exercise. Despite these novel findings,
no study has yet reported on the recovery characteristics from multi-jointed lower-body exercise in
middle-aged (35 to 55 years), resistance trained males. Indeed, Gordon et al. [
16
] advised that future
studies might adopt a more ecologically valid exercise protocol. Data from such a study would be
highly applicable to those athletes seeking to prolong their athletic careers. Consequently, the primary
aim of the study was to determine the time course to recovery from EIMD in young and middle-aged
resistance trained males. A secondary purpose was to determine if the recovery profile of middle-aged
males is altered by resistance training experience. Given the variability in the current data regarding
EIMD and ageing and a lack of studies in trained populations, we propose the null hypothesis, i.e.,
that the EIMD response would not be dierent between groups.
2. Materials and Methods
2.1. Design
The study used a two-way repeated measures design (age group x time), whereby participants
attended the laboratory on four separate occasions, the initial visit for estimations of body composition
and the back squat 1RM (Figure 1). On the same visit they were habituated with the measurements
of squatting peak power and MVC, VA, and resting doublet force during isometric knee extension.
Participants were considered ‘habituated’ when they could complete three consecutive repetitions that
produced power or force values each within 10% [
20
]. Participants returned to the laboratory 2–4 days
later for measurements comprising squats at 20% and 80% 1RM, MVC, VA, resting doublet force,
muscle soreness, and creatine kinase (CK) activity, and an exercise bout comprising 10
×
10 squats at
60% 1RM [21]. Repeated measures were then conducted 24 and 72 h after the initial exercise bout.
Sports 2019, 7 FOR PEER REVIEW 2
which suggests that older resistance-trained men might exhibit symptoms of EIMD that are not
dissimilar to their untrained counterparts.
Studies examining the recovery of older and younger untrained adults after muscle-damaging
exercise are equivocal. Some studies have reported greater symptoms of EIMD in younger, compared
to older, males [14,15], while others have observed greater EIMD in older (~59 to 66 years), compared
to younger, males (~23 years) (17). Moreover, a number of studies have reported no difference in
symptoms of EIMD after exercise for young populations (~19 years), compared to older populations
(~48 to 76 years) [6,16–19]. One confounding factor in the current literature might be the physical
activity and resistance training status of the participants. For example, when controlling for physical
activity, Buford et al. [18] noted that recovery from muscle-damaging unilateral plantar flexion was
similar among young (~23 years) and older (~76 years) adults. Despite the effectiveness of resistance
training in combating the age-associated losses, only one study has investigated the EIMD response
in older resistance trained males. Like Buford et al. [18], Gordon and colleagues [16] observed no
differences in indirect markers of EIMD between recreationally trained young (~22 years) and
middle-aged (~47 years) males after damaging knee extensor exercise. Despite these novel findings,
no study has yet reported on the recovery characteristics from multi-jointed lower-body exercise in
middle-aged (35 to 55 years), resistance trained males. Indeed, Gordon et al. [16] advised that future
studies might adopt a more ecologically valid exercise protocol. Data from such a study would be
highly applicable to those athletes seeking to prolong their athletic careers. Consequently, the
primary aim of the study was to determine the time course to recovery from EIMD in young and
middle-aged resistance trained males. A secondary purpose was to determine if the recovery profile
of middle-aged males is altered by resistance training experience. Given the variability in the current
data regarding EIMD and ageing and a lack of studies in trained populations, we propose the null
hypothesis, i.e., that the EIMD response would not be different between groups.
2. Materials and Methods
2.1. Design
The study used a two-way repeated measures design (age group x time), whereby participants
attended the laboratory on four separate occasions, the initial visit for estimations of body
composition and the back squat 1RM (Figure 1). On the same visit they were habituated with the
measurements of squatting peak power and MVC, VA, and resting doublet force during isometric
knee extension. Participants were considered ‘habituated’ when they could complete three
consecutive repetitions that produced power or force values each within 10% [20]. Participants
returned to the laboratory 2–4 days later for measurements comprising squats at 20% and 80% 1RM,
MVC, VA, resting doublet force, muscle soreness, and creatine kinase (CK) activity, and an exercise
bout comprising 10 × 10 squats at 60% 1RM [21]. Repeated measures were then conducted 24 and 72
h after the initial exercise bout.
Figure 1. Schematic of study design.
Habituationn and
anthropometry
Markers of EIMD
Muscle damaging exercise
Markers of EIMD
Markers of EIMD
48-96 hrs
72 hrs
24 hrs
Figure 1. Schematic of study design.
Sports 2019,7, 132 3 of 13
2.2. Participants
Nine young resistance trained (YG; range: 21 to 25 years), nine middle-aged (MT; range: 35 to
54 years) resistance trained, and nine untrained middle-age males (MU; range: 35 to 53 years) were
recruited for this study using convenience sampling. Thirty-five years was selected as the lower
boundary for the middle-aged group because it is the entry age for ‘Masters’ athletes (see British
Masters Athletic Federation and World Masters Athletics). As age-related studies typically use older
groups (60 years and over), 55 was selected as the upper-limit for the middle-aged group. An overall
sample size of approximately 27 (nine per group) was estimated using Batterham and Atkinson’s [
22
]
nomogram. This was calculated using a coecient of variation and typical change of 6.1% [
23
] and 5%,
respectively. The YG and MT had a minimum of two years’ resistance training experience and regularly
used squats as part of their resistance training programmes. The MU group had no resistance training
experience, but was screened by the lead researcher to ensure they could perform the correct squat
technique. All participants had been active in sport for a minimum of two years and were competitive.
Participants completed a pre-test health questionnaire and provided written consent for the study,
which was approved by the Ethics Committee of the Faculty of Life Sciences at the host institution.
Participants were instructed not to consume any ergogenic supplements (for example, caeine) on the
day of testing and to refrain from exercise, other than that performed as part of the study, throughout
their involvement.
2.3. Procedures
2.3.1. Anthropometric Measurements
Body density was estimated via skinfold thickness measurements (Harpenden, British Indicators,
Burgess Hill, UK) taken at the triceps, axilla, abdominal, suprailiac, chest, subscapular, and
mid-thigh [
24
]. Body fat percentage (%BF) was estimated [
25
] from which quantities (kg) of fat-mass
(FM) and fat-free mass (FFM) were derived.
2.3.2. Resistance Training History and Sports Participation
The YG and MT participants completed a questionnaire to record how many years they had
participated in regular resistance training, their weekly training frequency and session duration,
and the main reason for their training. A second questionnaire detailed how many years they had
participated in organised sport, their weekly frequency and session duration, and the type of sport
they in which participated (i.e., team, endurance, racket, or other).
2.3.3. Maximal Strength Testing
The 1RM for squat exercise was predicted using a three-repetition maximum (3RM) protocol.
Participants performed 8–10 repetitions with 50% of their estimated 1RM, followed by 3–5 repetitions
with 85% of their estimated 1RM. The load was then set at the approximate 3RM and the participants
performed three repetitions. The load was progressively increased until the participant could no longer
perform a complete repetition. The final load lifted was then used with the following equation [
26
] to
estimate the 1RM squat load:
1RM =(100 ×3RM load lifted)/[48.8 +(53.8 ×2.718280.075 ×repetitions). (1)
The above equation has been reported to yield accurate 1RM predictions (r=0.969, 0.02% dierent
from direct 1RM) [27].
2.3.4. Indirect Markers of Muscle Damage
Perceived muscle soreness of the knee extensors was measured using a 0–10 visual analogue scale
(VAS). Plasma CK activity was also determined from a capillary blood sample. A 30
µ
L sample of
Sports 2019,7, 132 4 of 13
whole blood was collected into a heparinised capillary tube and pipetted onto a test strip for analysis
(Reflotron, Type 4, Boehringer Mannheim, Mannheim, Germany).
2.3.5. Assessment of Maximal Voluntary Contraction and Voluntary Activation
Before undertaking the MVC and VA assessments, participants performed a warm-up comprising
five minutes of cycling at 100 W (Lode, Corival, Groningen, Netherlands). An isometric dynamometer
(Biodex, Multi-joint system 3, Biodex Medical, New York, NY, USA) was employed to measure the
force of the participant’s dominant knee extensor at 80
knee flexion. To prevent extraneous body
movements, Velcro straps were applied tightly across the chest and thigh. Participants were provided
with strong verbal encouragement and real-time feedback via the PC monitor.
The knee extensors were electrically stimulated (5 s with two 100 Hz single square impulses
(doublet); Digitimer, D57, Hertfordshire, UK) using two 5
×
13 cm moistened surface electrodes
(Axelgaard Manufacturing Co., Ltd., Fallbrook, CA, USA); one placed distally over the quadriceps
and the other proximally over the upper quadricep. During optimisation, the amplitude of a doublet
was progressively increased, starting at 50 amps, until a point where no further increases in intensity
resulted in an increase in resting doublet force. Initially, a 230 volt electrically evoked doublet (set 20%
above the value required to evoke a resting muscle doublet of maximum amplitude) was applied to
the resting muscle (resting doublet) at 1 s. The resting doublet was used to elucidate any peripheral
alterations that might have occurred as a result of the squatting protocol [
21
]. Participants then
performed a 4 s MVC before a doublet, which was applied at the isometric plateau (superimposed
doublet). The MVC was taken as the average force over 50 ms (AcqKnowledge 3 software, Biopac
Systems, Massachusetts, MA, USA) before the superimposed doublet was applied. VA was calculated
according to the interpolated doublet ratio using the equation:
VA (%) =[1 (size of superimposed doublet/size of resting doublet)] ×100. (2)
A similar procedure has been deemed a reliable method (CV =3.38%) for assessing VA [28].
2.3.6. Assessment of Peak Power During Squat
Peak power was assessed at loads corresponding to 20% and 80% 1RM during the back squat
exercise using a rotary encoder (FitroDyne, Fitronic, Bratislava, Slovakia), the procedures for which
have been described elsewhere [
5
,
23
]. The FitroDyne has been shown to produce reliable intra- and
inter-day measures of peak power (coecient of variation =3.9–6.1%) at the selected loads [23].
2.3.7. Muscle-Damaging Exercise Protocol
This consisted of 10
×
10 repetitions of squat exercise at a load corresponding to 60% 1RM with 120 s
rest between sets [
21
]. Each repetition was performed in the manner outlined above. A similar protocol
has successfully induced symptoms of muscle damage in previous research [
21
,
29
]. The FitroDyne was
used to calculate the power for each repetition in the manner outlined above. The average peak power
per repetition was used to elucidate the influence of exercise intensity on recovery profiles between
groups. One participant from the MU group was unable to complete sets 8, 9, and 10 at 60% 1RM, thus
the load was reduced by 5 kg (50.1% 1RM) and power values were calculated accordingly.
2.4. Statistical Analyses
Comparisons of categorical training history and sport participation variables by group were made
using a chi-squared (
χ2
) test of association. All other data were analysed using the eect size (ES)
with 90% confidence intervals (CI) [
30
]. Magnitude-based inference statistics were used to provide
information on the size of the dierences, allowing for a more practical and meaningful explanation of
the data [
31
]. Thresholds for the magnitude of the observed change for each variable were determined
as the within-participant standard deviation in that variable
×
0.2, 0.6, 1.2, and 2 for a small, moderate,
Sports 2019,7, 132 5 of 13
large, and very large eect [
32
]. Threshold probabilities for a meaningful eect, based on the 90%
confidence limits (CL) were as follows: Less than 0.5% most unlikely, 0.5–5% very unlikely, 5–25% unlikely,
25–75% possibly, 75–95% likely, 95–99.5% very likely, and >99.5% most likely. Eects with confidence
limits across a likely small positive or negative change were classified as unclear [
30
]. All calculations
were completed using predesigned spreadsheets (www.sportsci.org). Data are presented as ES, lower
CI, and upper CI.
3. Results
3.1. Biometric Measures and Training History
Age and sum of skinfolds were most likely and likely higher, respectively, in the MT groups
compared to the YG group (Table 1). Dierences in FM and body fat percentage between the YG and
MT groups were very likely, while mass and squat 1RM were unclear. Age and FFM dierences between
the MT and MU groups were likely moderate, whilst all other biometric characteristics demonstrated
unclear dierences.
The MT group had most likely regularly resistance trained for longer than the YG (ES 2.29, CI 1.46,
3.13; Table 2), though their training was associated with a lower weekly frequency (
χ2
=32.5, p<0.05)
and shorter session duration (
χ2
=36.4, p<0.05). Moreover, the MT group typically chose resistance
training for strength and fat loss, whereas the YG trained for strength (χ2=31.8, p<0.05).
Table 1.
Biometric characteristics (mean
±
SD) and comparisons of young (YG) and middle-aged
trained (MT) and untrained (MU) groups.
Measure Group Comparison
YG (n=9) MT (n=9) MU (n=9) YG v MT MT v MU
Age (years) 22.3 ±1.7 39.9 ±6.2 44.4 ±6.3 Most likely
3.70 (2.87, 4.53)
Likely
0.71 (0.10, 1.52)
Mass (kg) 82.0 ±9.0 79.1 ±10.3 83.4 ±9.56 Unclear
0.29 (1.10, 0.52)
Unclear
0.42 (0.39, 1.23)
Fat-free mass
(kg) 71.4 ±7.9 63.9 ±6.5 68.6 ±7.1 Very likely
1.02 (
1.83,
0.22)
Likely
0.68 (0.13, 1.49)
Fat-mass (kg) 10.5 ±4.5 15.2 ±5.7 14.8 ±7.0 Likely
0.89 (0.09, 1.70)
Unclear
0.07 (0.88, 0.74)
Body fat (%) 12.8 ±4.7 18.8 ±5.8 17.4 ±6.7 Very likely
1.13 (0.32, 1.94)
Unclear
0.23 (1.04, 0.58)
Sum of
skinfolds (mm) 82.3 ±24.6 102.4 ±31.9 91.7 ±32.7 Likely
0.69 (0.12, 1.50)
Unclear
0.32 (1.13, 0.48)
Squat 1RM (kg)
130.8 ±26.8 109.3 ±22.5 98.4 ±14.25 Unclear
0.85 (
1.65,
0.04)
Unclear
0.56 (1.37, 0.25)
The comparison panel details the qualitative descriptor, eect size, and upper and lower confidence limits.
Table 2. Resistance training characteristics of the young (YG) and middle-aged trained groups (MT).
Resistance Training Characteristics YG (n=9) MT (n=9)
Years of resistance training (mean ±SD) 4.6 ±1.3 18.0 ±5.6
Weekly frequency *
1 to 2 2 (22.2) 6 (66.7)
3 to 4 4 (44.4) 2 (22.2)
5+3 (33.3) 1 (11.1)
Session duration *
0 to 30 min 0 (0.0) 1 (11.1)
31 to 60 min
3 (33.3) 7 (77.8)
61 to 90 min
5 (55.6) 1 (11.1)
90+min 1 (11.1) 0 (0.0)
Reason for resistance training *
Strength 6 (66.7) 4 (44.4)
Hypertrophy
1 (11.1) 0 (0.0)
Fat loss 1 (11.1) 4 (44.4)
Health 1 (11.1) 1 (11.1)
* Categorical variables are significantly associated (p<0.05). Bracketsdenote percentage of responses in each category.
Sports 2019,7, 132 6 of 13
There were very likely large and moderate dierences in sports participation for the MT compared
to the YG and MU, respectively, with MT having more years compared to the YG (ES 1.47, CI 0.66, 2.28)
and less than the MU group (ES 1.17, CI 0.36, 1.98; Table 3). No relationship (p>0.05) was observed
between groups for weekly frequency, session duration, or type of sport played.
Table 3. Sports participation characteristics of the young and middle-aged trained groups.
Sports Participation Characteristics YG (n=9) MT (n=9) MU (n=9)
Years of sports participation (mean ±SD) 11.2 ±4.8 22.0 ±7.8 30.3 ±7.8
Weekly frequency
1 to 2 4 (44.4) 2 (22.2) 0 (0.0)
3 to 4 4 (44.4) 4 (44.4) 6 (66.7)
5+1 (11.1) 3 (33.3) 3 (33.3)
Session duration
0 to 30 min 0 (0.0) 0 (0.0) 0 (0.0)
31 to 60 min 3 (33.3) 4 (44.4) 7 (77.8)
61 to 90 min 3 (33.3) 3 (33.3) 1 (11.1)
90+min 3 (33.3) 2 (22.2) 1 (11.1)
Type of sport
Team 5 (55.6) 3 (33.3) 3 (33.3)
Endurance 3 (33.3) 5 (55.6) 4 (44.4)
Racket 0 (0.0) 1 (11.1) 2 (22.2)
Other 1 (11.1) 0 (0.0) 0 (0.0)
3.2. External Load Response during the Muscle-Damaging Protocol
There was a likely moderate lower average peak power (ES
0.71 CI
1.53, 0.10) in the MT (603.2
±
162.6 W) compared to the YG (770.4
±
278.0 W). Dierences between the MT and MU (547.0
±
75.0 W)
groups were unclear (ES 0.43, CI 1.25, 0.39).
3.3. Indirect Markers of Muscle Damage
At Pre, dierences in muscle soreness between the YG and MT and MT and MU were unclear
(ES 0.00, CI
0.81, 0.81 and ES 0.42, CI
0.39, 1.22, respectively; Figure 2). When the three groups were
combined, perceived muscle soreness demonstrated most likely very large (ES 4.20, CI 3.74, 4.65) increases
at 24 h and, likewise (ES 1.82, CI 1.36, 2.27), at 72 h after muscle-damaging exercise. Between-group
dierences for the YG and MT comparison were unclear at 24 and 72 h after muscle-damaging exercise.
Increases in muscle soreness were likely moderately higher in the MU group compared to the MT group
at 24 and 72 h.
Sports 2019, 7 FOR PEER REVIEW 6
There were very likely large and moderate differences in sports participation for the MT compared
to the YG and MU, respectively, with MT having more years compared to the YG (ES 1.47, CI 0.66,
2.28) and less than the MU group (ES 1.17, CI 0.36, 1.98; Table 3). No relationship (p > 0.05) was
observed between groups for weekly frequency, session duration, or type of sport played.
Table 3. Sports participation characteristics of the young and middle-aged trained groups.
Sports Participation Cha
r
acteristics YG (n = 9) MT (n = 9) MU (n = 9)
Years of sports participation (mean ± SD) 11.2 ± 4.8 22.0 ± 7.8 30.3 ± 7.8
Weekly frequency
1 to 2 4 (44.4) 2 (22.2) 0 (0.0)
3 to 4 4 (44.4) 4 (44.4) 6 (66.7)
5+ 1 (11.1) 3 (33.3) 3 (33.3)
Session duration
0 to 30 min 0 (0.0) 0 (0.0) 0 (0.0)
31 to 60 min 3 (33.3) 4 (44.4) 7 (77.8)
61 to 90 min 3 (33.3) 3 (33.3) 1 (11.1)
90+ min 3 (33.3) 2 (22.2) 1 (11.1)
Type of sport
Team 5 (55.6) 3 (33.3) 3 (33.3)
Endurance 3 (33.3) 5 (55.6) 4 (44.4)
Racket 0 (0.0) 1 (11.1) 2 (22.2)
Other 1 (11.1) 0 (0.0) 0 (0.0)
3.2. External Load Response during the Muscle-Damaging Protocol
There was a likely moderate lower average peak power (ES 0.71 CI 1.53, 0.10) in the MT (603.2
± 162.6 W) compared to the YG (770.4 ± 278.0 W). Differences between the MT and MU (547.0 ± 75.0
W) groups were unclear (ES 0.43, CI 1.25, 0.39).
3.3. Indirect Markers of Muscle Damage
At Pre, differences in muscle soreness between the YG and MT and MT and MU were unclear
(ES 0.00, CI 0.81, 0.81 and ES 0.42, CI 0.39, 1.22, respectively; Figure 2). When the three groups were
combined, perceived muscle soreness demonstrated most likely very large (ES 4.20, CI 3.74, 4.65)
increases at 24 h and, likewise (ES 1.82, CI 1.36, 2.27), at 72 h after muscle-damaging exercise.
Between-group differences for the YG and MT comparison were unclear at 24 and 72 h after muscle-
damaging exercise. Increases in muscle soreness were likely moderately higher in the MU group
compared to the MT group at 24 and 72 h.
Figure 2. Changes in perceived muscle soreness between YG, MT, and MU at pre, 24, and 72 h after
resistance exercise. The panel above details the qualitative descriptor, effect size, and upper and lower
confidence limits.
Figure 2.
Changes in perceived muscle soreness between YG, MT, and MU at pre, 24, and 72 h after
resistance exercise. The panel above details the qualitative descriptor, eect size, and upper and lower
confidence limits.
Sports 2019,7, 132 7 of 13
Dierences in CK activity at Pre for YG and MT and MT and MU comparisons were unclear
(ES
0.41, CI
1.21, 0.40 and ES
0.44, CI
1.25, 0.38, respectively; Figure 3). The increase in plasma
CK activity for the three groups combined was very likely moderate (ES 1.19, CI 0.73, 1.64) and likely small
(ES 0.59, CI 0.13, 1.05) at 24 and 72 h, respectively, compared to Pre. Dierences in plasma CK activity
over time were unclear between the YG and MT groups. Plasma CK activity was likely moderately higher
in the MU group compared to the MT group at 24 h, though dierences between the groups were
unclear at 72 h.
Sports 2019, 7 FOR PEER REVIEW 7
Differences in CK activity at Pre for YG and MT and MT and MU comparisons were unclear (ES
0.41, CI 1.21, 0.40 and ES 0.44, CI 1.25, 0.38, respectively; Figure 3). The increase in plasma CK
activity for the three groups combined was very likely moderate (ES 1.19, CI 0.73, 1.64) and likely small
(ES 0.59, CI 0.13, 1.05) at 24 and 72 h, respectively, compared to Pre. Differences in plasma CK activity
over time were unclear between the YG and MT groups. Plasma CK activity was likely moderately
higher in the MU group compared to the MT group at 24 h, though differences between the groups
were unclear at 72 h.
Figure 3. Changes in plasma creatine kinase activity between YG, MT, and MU at Pre, 24, and 72 h
after resistance exercise. The panel above details the qualitative descriptor, effect size, and upper and
lower confidence limits.
At Pre, differences in MVC force were likely moderate and unclear for the YG compared to MT (ES
0.80, CI 1.61, 0.01) and MT compared to MU (ES 0.27, CI 0.56, 1.10), respectively (Figure 4). MVC
force had very likely moderate (ES 0.71, CI 1.16, 0.26) and likely small (ES 0.39, CI 0.84, 0.06)
decreases at 24 and 72 h after muscle-damaging exercise. Likely and very likely moderate reductions in
MVC force were observed in the MT group compared to the YG groups at 24 and 72 h, respectively.
At 24 and 72 h, differences between the MT and MU groups were unclear.
Figure 4. Changes in maximal voluntary contraction force between YG, MT, and MU at Pre, 0, 24, and
72 h after resistance exercise. The panel above details the qualitative descriptor, effect size, and upper
and lower confidence limits.
0
200
400
600
800
1000
1200
1400
1600
Pre 24h 72h
Creatine kinase (U/l)
YG MT MU
Figure 3.
Changes in plasma creatine kinase activity between YG, MT, and MU at Pre, 24, and 72 h
after resistance exercise. The panel above details the qualitative descriptor, eect size, and upper and
lower confidence limits.
At Pre, dierences in MVC force were likely moderate and unclear for the YG compared to MT
(ES
0.80, CI
1.61, 0.01) and MT compared to MU (ES 0.27, CI
0.56, 1.10), respectively (Figure 4).
MVC force had very likely moderate (ES
0.71, CI
1.16,
0.26) and likely small (ES
0.39, CI
0.84, 0.06)
decreases at 24 and 72 h after muscle-damaging exercise. Likely and very likely moderate reductions in
MVC force were observed in the MT group compared to the YG groups at 24 and 72 h, respectively.
At 24 and 72 h, dierences between the MT and MU groups were unclear.
Sports 2019, 7 FOR PEER REVIEW 7
Differences in CK activity at Pre for YG and MT and MT and MU comparisons were unclear (ES
0.41, CI 1.21, 0.40 and ES 0.44, CI 1.25, 0.38, respectively; Figure 3). The increase in plasma CK
activity for the three groups combined was very likely moderate (ES 1.19, CI 0.73, 1.64) and likely small
(ES 0.59, CI 0.13, 1.05) at 24 and 72 h, respectively, compared to Pre. Differences in plasma CK activity
over time were unclear between the YG and MT groups. Plasma CK activity was likely moderately
higher in the MU group compared to the MT group at 24 h, though differences between the groups
were unclear at 72 h.
Figure 3. Changes in plasma creatine kinase activity between YG, MT, and MU at Pre, 24, and 72 h
after resistance exercise. The panel above details the qualitative descriptor, effect size, and upper and
lower confidence limits.
At Pre, differences in MVC force were likely moderate and unclear for the YG compared to MT (ES
0.80, CI 1.61, 0.01) and MT compared to MU (ES 0.27, CI 0.56, 1.10), respectively (Figure 4). MVC
force had very likely moderate (ES 0.71, CI 1.16, 0.26) and likely small (ES 0.39, CI 0.84, 0.06)
decreases at 24 and 72 h after muscle-damaging exercise. Likely and very likely moderate reductions in
MVC force were observed in the MT group compared to the YG groups at 24 and 72 h, respectively.
At 24 and 72 h, differences between the MT and MU groups were unclear.
Figure 4. Changes in maximal voluntary contraction force between YG, MT, and MU at Pre, 0, 24, and
72 h after resistance exercise. The panel above details the qualitative descriptor, effect size, and upper
and lower confidence limits.
0
200
400
600
800
1000
1200
1400
1600
Pre 24h 72h
Creatine kinase (U/l)
YG MT MU
Figure 4.
Changes in maximal voluntary contraction force between YG, MT, and MU at Pre, 0, 24, and
72 h after resistance exercise. The panel above details the qualitative descriptor, eect size, and upper
and lower confidence limits.
Sports 2019,7, 132 8 of 13
Dierences in VA at Pre were unclear for YG compared to MT (ES 0.03, CI
0.77, 0.84) and MT
compared to MU (ES 0.07, CI
0.76, 0.90; Figure 5). When all groups were combined VA decreased over
time, with values at 24 and 72 h demonstrating very likely moderate decreases (ES
0.87, CI
1.33,
0.41
and ES
0.88, CI
1.34,
0.41, respectively). Dierences between groups were unclear at all time-points.
Sports 2019, 7 FOR PEER REVIEW 8
Differences in VA at Pre were unclear for YG compared to MT (ES 0.03, CI 0.77, 0.84) and MT
compared to MU (ES 0.07, CI 0.76, 0.90; Figure 5). When all groups were combined VA decreased
over time, with values at 24 and 72 h demonstrating very likely moderate decreases (ES 0.87, CI 1.33,
0.41 and ES 0.88, CI 1.34, 0.41, respectively). Differences between groups were unclear at all time-
points.
Figure 5. Changes in voluntary activation between YG, MT and MU at Pre, 24, and 72 h after resistance
exercise. The panel above details the qualitative descriptor, effect size, and upper and lower
confidence limits.
Higher mean resting doublet values for the YG were likely moderate compared to the MT (ES
0.96 CI 1.77, 0.14; Figure 6). Similarly, higher values for MU (ES 0.95, CI 0.12, 1.78) were likely
moderate compared to the MT group. Mean doublet values were likely small and unclear at 24 and 72
h, respectively, (ES 0.52, CI 0.98, 0.06 and ES 0.04, CI 0.50, 0.42, respectively) after squatting
exercise. Differences in resting doublet were very likely moderate and likely moderate between YG and
MT groups at 24 and 72 h, respectively. MT and MU comparisons were unclear at 24 and 72 h.
Figure 6. Changes in resting doublet force between YG, MT and MU at Pre, 24, and 72 h after
resistance exercise. The panel above details the qualitative descriptor, effect size, and upper and lower
confidence limits.
75
80
85
90
95
100
Pre 24h 72h
Voluntary activation (%)
YG MT MU
Figure 5.
Changes in voluntary activation between YG, MT and MU at Pre, 24, and 72 h after
resistance exercise. The panel above details the qualitative descriptor, eect size, and upper and lower
confidence limits.
Higher mean resting doublet values for the YG were likely moderate compared to the MT (ES
0.96
CI
1.77, 0.14; Figure 6). Similarly, higher values for MU (ES 0.95, CI 0.12, 1.78) were likely moderate
compared to the MT group. Mean doublet values were likely small and unclear at 24 and 72 h, respectively,
(ES
0.52, CI
0.98,
0.06 and ES
0.04, CI
0.50, 0.42, respectively) after squatting exercise. Dierences
in resting doublet were very likely moderate and likely moderate between YG and MT groups at 24 and
72 h, respectively. MT and MU comparisons were unclear at 24 and 72 h.
Sports 2019, 7 FOR PEER REVIEW 8
Differences in VA at Pre were unclear for YG compared to MT (ES 0.03, CI 0.77, 0.84) and MT
compared to MU (ES 0.07, CI 0.76, 0.90; Figure 5). When all groups were combined VA decreased
over time, with values at 24 and 72 h demonstrating very likely moderate decreases (ES 0.87, CI 1.33,
0.41 and ES 0.88, CI 1.34, 0.41, respectively). Differences between groups were unclear at all time-
points.
Figure 5. Changes in voluntary activation between YG, MT and MU at Pre, 24, and 72 h after resistance
exercise. The panel above details the qualitative descriptor, effect size, and upper and lower
confidence limits.
Higher mean resting doublet values for the YG were likely moderate compared to the MT (ES
0.96 CI 1.77, 0.14; Figure 6). Similarly, higher values for MU (ES 0.95, CI 0.12, 1.78) were likely
moderate compared to the MT group. Mean doublet values were likely small and unclear at 24 and 72
h, respectively, (ES 0.52, CI 0.98, 0.06 and ES 0.04, CI 0.50, 0.42, respectively) after squatting
exercise. Differences in resting doublet were very likely moderate and likely moderate between YG and
MT groups at 24 and 72 h, respectively. MT and MU comparisons were unclear at 24 and 72 h.
Figure 6. Changes in resting doublet force between YG, MT and MU at Pre, 24, and 72 h after
resistance exercise. The panel above details the qualitative descriptor, effect size, and upper and lower
confidence limits.
75
80
85
90
95
100
Pre 24h 72h
Voluntary activation (%)
YG MT MU
Figure 6.
Changes in resting doublet force between YG, MT and MU at Pre, 24, and 72 h after
resistance exercise. The panel above details the qualitative descriptor, eect size, and upper and lower
confidence limits.
Sports 2019,7, 132 9 of 13
3.4. Peak Power during Squat Exercise
At Pre, avery likely moderate lower peak power was at 20% and 80% 1RM (ES
1.03, CI
1.84,
0.22 and ES
1.03, CI
1.84,
0.21, respectively) was observed in the MT compared to YG (Table 4).
Dierences at Pre for MT and MU were most likely very large and unclear for 20% and 80% 1RM (ES
3.34,
CI
4.18,
2.50 and ES
0.47, CI
1.28, 0.33, respectively). When all groups were combined, peak power
for 20% and 80% 1RM demonstrated possibly small (ES
0.25, CI
0.71, 0.20 and ES
0.36, CI
0.81, 0.09,
respectively) and unclear (ES
0.23, CI
0.69, 0.22 and ES
0.19, CI
0.64, 0.26, respectively) decrements
at 24 and 72 h, respectively. For 20% and 80% 1RM, between group dierences at 24 and 72 h were very
likely moderate between the YG and MT groups. Similarly, reductions in 20% 1RM peak power at 24
and 72 h for the MT vs. MU comparison were very likely moderate. Peak power at 80% 1RM illustrated
likely moderate and very likely large dierences at 24 and 72 h, respectively.
Table 4. Peak power at Pre, 24 and 72 h.
Intensity Group Pre 24 h 72 h Comparison (90% CI)
Pre v 24 h Pre v 72 h
20% 1RM
(W)
YG 507.9 ±134.6 473.8 ±119.9 476.6 ±119.7 YG v MT
Very likely Very likely
MT 387.4 ±87.9 360.3 ±76.1 366.3 ±76.4
1.07(1.85, 0.28) 1.04 (1.82, 0.25)
MT v MU
MU 320.7 ±47.9 291.7 ±40.1 289.7 ±40.2 Very likely Very likely
1.06 (1.84, 0.27) 1.17 (1.96, 0.39)
80% 1RM
(W)
YG 1295.3 ±369.1 1207.5 ±328.2 1275.9 ±338.3 YG v MT
Very likely Very likely
MT 977.1 ±211.1 869.8 ±195.0 964.9 ±212.1
1.07 (1.96, 0.39) 1.04 (1.83, 0.25)
MT v MU
MU 886.0 ±163.2 746.7 ±153.3 735.1 ±134.8 Likely Very likely
0.67 (1.45, 0.12) 1.22 (2.01, 0.43)
The comparison panel details the qualitative descriptor, eect size, and upper and lower confidence limits.
4. Discussion
Contrary to our hypothesis, the current findings highlight the magnitude of exercise-induced
muscle damage and time-course of recovery after lower body resistance exercise is greater in trained
middle-aged males than their young counterparts. Moreover, regardless of resistance training
experience, middle-aged males experienced like symptoms of muscle damage and a similar recovery
profile in the days after.
4.1. Confirmation of EIMD
The small to moderate loss of force at 24 and 72 h observed in the current study confirms that
the prescribed lower-body resistance exercise caused EIMD. Although not indicative of myofibrillar
disruption [
7
,
8
], the small to very large increases in muscle soreness and CK activity indicate that
tissue damage occurred after squatting exercise. The losses in MVC support previous observations of
isometric strength loss after lower-body eccentric exercise in younger resistance trained males [
21
].
The reductions in MVC at 24 h possibly owe to both peripheral and central impairments, given the
contemporaneous decrements in resting doublet and VA. However, that resting doublet scores were
recovered by 72 h, but VA remained suppressed, suggests that the reductions in MVC at the later
time point were caused by central alterations. Potential central mechanisms include a reduction
in drive to the muscle caused by neural impairments and reduction in excitability to the alpha
motor-neuron [28,33].
Sports 2019,7, 132 10 of 13
4.2. Changes in Indirect Markers of EIMD in Trained Young and Middle-Aged Males
That dierences between trained groups on plasma CK activity after resistance exercise were
unclear rearms the findings of previous studies [
15
,
18
,
34
], suggesting that membrane permeability is
similar between trained young and middle age groups. Likewise, the comparable changes in muscle
soreness observed in the two resistance trained groups is consistent with the work of Buford et al. [
18
],
albeit in a non-resistance trained sample, in the plantar flexors, though contradictory to reports of
greater soreness experienced by younger males after muscle-damaging elbow flexor exercise [
14
,
19
].
Increases in muscle soreness might reflect damage to connective tissue and decreases in range of
motion, rather than damage to the contractile machinery per se [
7
,
8
]. Consequently, these data indicate
that CK and muscle soreness responses to lower-limb muscle damaging exercise are similar in young
and middle-aged resistance trained males.
4.3. Changes in Muscle Function in Trained Young and Middle-Aged Males
Reductions in MVC, VA, and resting doublet occurred in both resistance trained groups after EIMD.
The finding that Pre VA values were not dierent between groups contrasts previous suggestions that
older healthy adults are unable to activate the muscle to the same extent as their young counterparts [
35
],
possibly owing to the trained nature of the MT group [
36
]. That the time course of VA recovery after
high volume squatting exercise was not dierent between the MT and YG groups is also a novel
finding. The moderately greater reductions in MVC in the MT group, compared to the YG group after
EIMD, appear to be mediated by peripheral alterations (i.e., disruptions of sarcomeres and impaired
excitation-contraction coupling), as reflected by the lower resting doublet values in the older trained
participants. Given that dierences in VA were unclear between the resistance trained groups after
EIMD suggests that central alterations are not responsible for the greater reductions in MVC in the
MT group.
The lower Pre peak power values at 20% and 80% 1RM in the MT group, compared to the YG
group, are similar to those previously reported in resistance trained middle-aged males [
5
]. For the
first time, this study has highlighted that the decrements in peak power after EIMD are of a greater
magnitude in middle-aged males, compared to young resistance trained males. Work in young athletes
indicates that lower-body power output has strong relationships with a variety of sporting tasks [
37
,
38
].
Thus, it is plausible that the impaired power output due to EIMD may inhibit these movements in
trained young and middle-aged males. Applied practitioners should therefore be cognisant of this
and consider adopting dierent recovery practices for young and middle-aged male athletes after
muscle-damaging lower-limb exercise.
4.4. Dierences in Recovery Between Trained and Untrained Middle-Aged Males
The two middle-aged groups produced similar peak power during the muscle-damaging protocol,
which was followed by similar changes in MVC, VA, resting doublet, and CK. The repeated bout eect
(RBE) [
7
,
10
] suggests that resistance trained males should experience less muscle damage after eccentric
exercise compared to untrained males. However, the attenuated protection oered to the muscle with
ageing [
12
,
13
] might explain the similar recovery profiles in these age groups. Moreover, the similar
sporting characteristics of the two middle-aged groups might also explain why both demonstrated
a comparable recovery profile. That is, the training experienced by both groups during their sports
participation might have provided a similar protection to the muscle-damaging squatting exercise.
A further explanation might be owed to the similar peak power produced during the muscle-damaging
protocol. It has been noted previously that the magnitude of EIMD and recovery were positively
related to the workload during the muscle damaging protocol in young and older adults [
39
]. Given
that both middle-aged groups produced a similar peak power during the exercise protocol, it is perhaps
not unexpected that the recovery profile was similar. After high volume squatting, dierences between
middle-aged groups in perceived muscle soreness and peak power were moderate to large. After
Sports 2019,7, 132 11 of 13
muscle damaging exercise, the MU group demonstrated greater losses in peak power compared to the
MT group. It is plausible that the resistance training experience of the MT group served to preserve or
enhance the type 2 fiber cross-sectional area [
40
], thus accounting for their smaller losses in peak power.
Consequently, resistance training in middle-aged males might help to maintain lower-body peak power
after muscle-damaging exercise, but does not appear to alter other indirect markers of EIMD.
4.5. Limitations
Readers should be aware of the cross-sectional nature of this study. That is, cause and eect
cannot directly be established, but rather, only associations between age groups and dierent training
status. However, given the large dierences between age groups (>18 years), designing a study that
spanned over ~18 years would be unfeasible. Whilst the high variability in plasma CK in our sample
is concerning, it should be noted that CK alterations show a poor temporal pattern with muscle
function [
41
]. As such, the CK alterations should be used to confirm tissue damage, rather than indicate
the magnitude of muscle damage.
5. Conclusions
This study reports that the magnitude of EIMD, as indicated by a reduction in muscle function,
and time-course of recovery after high volume resistance exercise is greater in trained middle-aged
males compared to their young counterparts. Practically, trained middle-aged males should be
cognisant of requiring greater recovery time and adopt appropriate strategies. Moreover, resistance
training in middle-aged males could attenuate the losses in peak power after high volume squatting
exercise, but does not alter the recovery profile of other indirect markers of muscle damage. Applied
practitioners should be mindful of these alterations in trained and untrained middle-aged males and
should programme training accordingly.
Author Contributions:
Conceptualization, J.F.T.F., K.L.L. and C.T.; Methodology, J.F.T.F., K.L.L. and C.T.; Formal
Analysis, J.F.T.F.; Investigation, J.F.T.F.; Resources, J.F.T.F.; Data Curation, J.F.T.F.; Writing—Original Draft
Preparation, J.F.T.F.; Writing—Review & Editing, J.F.T.F., K.L.L. and C.T.; Supervision, K.L.L. and C.T.
Funding: This research received no external funding.
Conflicts of Interest: There are no conflict of interest.
References
1.
Oce for National Statistics. National Population Projections: 2014-Based Statistical Bulletin.
Available online: https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/
populationprojections/bulletins/nationalpopulationprojections/2015-10-29 (accessed on 28 May 2019).
2.
Pantoja, P.D.; Saez De Villarreal, E.; Brisswalter, J.; Peyr
é
-Tartaruga, L.A.; Morin, J.B. Sprint acceleration
mechanics in masters athletes. Med. Sci. Sports Exerc. 2016,48, 2469–2474. [CrossRef] [PubMed]
3.
Frontera, W.R.; Suh, D.; Krivickas, L.S.; Hughes, V.A.; Goldstein, R.; Roubeno, R. Skeletal muscle fiber
quality in older men and women. Am. J. Physiol. Cell Physiol. 2000,279, C611–C618. [CrossRef] [PubMed]
4.
Candow, D.G.; Chilibeck, P.D. Dierences in size, strength, and power of upper and lower body muscle
groups in young and older men. J. Gerontol. Biol. Sci. 2005,60, 148–156. [CrossRef]
5.
Fernandes, J.F.T.; Lamb, K.L.; Twist, C. A comparison of load-velocity and load-power relationships between
well-trained young and middle-aged males during three popular resistance exercises. J. Strength Cond. Res.
2018,32, 1440–1447. [CrossRef]
6.
Roth, S.M.; Martel, G.F.; Ivey, F.M.; Lemmer, J.T.; Tracy, B.L.; Hurlbut, D.E.; Metter, E.J.; Hurley, B.F.;
Rogers, M.A. Ultrastructural muscle damage in young vs. older men after high-volume, heavy-resistance
strength training. J. Appl. Physiol. 1999,86, 1833–1840. [CrossRef]
7.
Hyldahl, R.D.; Hubal, M.J. Lengthening our perspective: Morphological, cellular, and molecular responses
to eccentric exercise. Muscle Nerve 2014,49, 155–170. [CrossRef]
8.
Damas, F.; Nosaka, K.; Libardi, C.A.; Chen, T.C.; Ugrinowitsch, C. Susceptibility to exercise-induced muscle
damage: A cluster analysis with a large sample. Int. J. Sports Med. 2016,37, 633–640. [CrossRef] [PubMed]
Sports 2019,7, 132 12 of 13
9.
Machado, M.; Willardson, J.M. Short recovery augments magnitude of muscle damage in high responders.
Med. Sci. Sports Exerc. 2010,42, 1370–1374. [CrossRef]
10.
Hyldahl, R.D.; Chen, T.C.; Nosaka, K. Mechanisms and mediators of the skeletal muscle repeated bout eect.
Exerc. Sport Sci. Rev. 2017,45, 24–33. [CrossRef]
11.
Nosaka, K.; Sakamoto, K.E.I.; Newton, M.; Sacco, P. How long does the protective eect on eccentric
exercise-induced muscle damage last? Med. Sci. Sports Exerc. 2001,33, 1490–1495. [CrossRef] [PubMed]
12.
Lavender, A.P.; Nosaka, K. Responses of old men to repeated bouts of eccentric exercise of the elbow flexors
in comparison with young men. Eur. J. Appl. Physiol. 2006,97, 619–626. [CrossRef]
13.
Gorianovas, G.; Skurvydas, A.; Streckis, V.; Brazaitis, M.; Kamandulis, S.; McHugh, M.P. Repeated bout eect
was more expressed in young adult males than in elderly males and boys. Biomed. Res. Int.
2013
,2013.
[CrossRef] [PubMed]
14.
Lavender, A.P.; Nosaka, K. Comparison between old and young men for changes in makers of muscle
damage following voluntary eccentric exercise of the elbow flexors. Appl. Physiol. Nutr. Metab.
2006
,31,
218–225. [CrossRef]
15.
Lavender, A.P.; Nosaka, K. Fluctuations of isometric force after eccentric exercise of the elbow flexors of
young, middle-aged, and old men. Eur. J. Appl. Physiol. 2007,100, 161–167. [CrossRef] [PubMed]
16.
Gordon, J., III; Homan, J.R.; Arroyo, E.; Varanoske, A.; Coker, N.; Gepner, Y.; Wells, A.; Stout, J.; Fukuda, D.
Comparisons in the recovery response from resistance exercise between young and middle-aged men.
J. Strength Cond. Res. 2017,31, 3454–3462. [CrossRef] [PubMed]
17.
Lavender, A.P.; Nosaka, K. Changes in markers of muscle damage of middle-aged and young men following
eccentric exercise of the elbow flexors. J. Sci. Med. Sport 2008,11, 124–131. [CrossRef]
18.
Buford, T.W.; MacNeil, R.G.; Clough, L.G.; Dirain, M.; Sandesara, B.; Pahor, M.; Manini, T.M.;
Leeuwenburgh, C. Active muscle regeneration following eccentric contraction-induced injury is similar
between healthy young and older adults. J. Appl. Physiol. 2014,116, 1481–1490. [CrossRef] [PubMed]
19.
Chapman, D.W.; Newton, M.; McGuigan, M.R.; Nosaka, K. Comparison between old and young men for
responses to fast velocity maximal lengthening contractions of the elbow flexors. Eur. J. Appl. Physiol.
2008
,
104, 531–539. [CrossRef]
20.
Batterham, A.; George, K. Reliability in evidence-based clinical practice: A primer for allied health
professionals. Phys. Sport 2003,4, 122–128. [CrossRef]
21.
Macdonald, G.Z.; Button, D.C.; Drinkwater, E.J.; Behm, D.G. Foam rolling as a recovery tool after an intense
bout of physical activity. Med. Sci. Sports Exerc. 2014,46, 131–142. [CrossRef]
22.
Batterham, A.M.; Atkinson, G. How big does my sample need to be? A primer on the murky world of
sample size estimation. Phys. Sport 2005,6, 153–163. [CrossRef]
23.
Fernandes, J.F.T.; Lamb, K.L.; Twist, C. The intra- and inter-day reproducibility of the FitroDyne as a measure
of multi-jointed muscle function. Isokinet. Exerc. Sci. 2016,24, 39–49. [CrossRef]
24.
Jackson, A.S.; Pollock, M.L. Generalized equations for predicting body density of men. Br. J. Nutr.
1978
,40,
497–504. [CrossRef] [PubMed]
25.
Heyward, V.H.; Wagner, D.R. Applied Body Composition Assessment; Human Kinetics: Champaign, IL,
USA, 2004.
26.
Wathen, D. Load Assingment. In Essenetials of Strength and Conditioning; Human Kinetics: Champaign, IL,
USA, 1994; pp. 435–446.
27.
LeSuer, D.; McCormick, J.; Mayhew, J.; Wasserstein, R.; Arnold, M. The accuracy of prediction equations for
estimating 1-RM performance in the bench press squat and deadlift. J. Strength Cond. Res.
1997
,11, 211–213.
28.
Morton, J.P.; Atkinson, G.; MacLaren, D.P.M.; Cable, N.T.; Gilbert, G.; Broome, C.; McArdle, A.; Drust, B.
Reliability of maximal muscle force and voluntary activation as markers of exercise-induced muscle damage.
Eur. J. Appl. Physiol. 2005,94, 541–548. [CrossRef] [PubMed]
29.
Burt, D.G.; Lamb, K.; Nicholas, C.; Twist, C. Eects of exercise-induced muscle damage on resting metabolic
rate, sub-maximal running and post-exercise oxygen consumption. Eur. J. Sport Sci.
2014
,14, 337–344.
[CrossRef] [PubMed]
30.
Hopkins, W.G.; Marshall, S.W.; Batterham, A.M.; Hanin, J. Progressive statistics for studies in sports medicine
and exercise science. Med. Sci. Sports Exerc. 2009,41, 3–12. [CrossRef]
31.
Batterham, A.M.; Hopkins, W.G. Making meaningful inferences about magnitudes. Int. J. Sports
Physiol. Perform. 2006,1, 50–57. [CrossRef]
Sports 2019,7, 132 13 of 13
32.
Cohen, J. Statistical Power Analysis for the Behavioral Science; Lawrence Earlbaum Associates: Hilsdale, NJ,
USA, 1988.
33.
Avela, J.; Kyröläinen, H.; Komi, P.V.; Rama, D. Reduced reflex sensitivity persists several days after
long-lasting stretch-shortening cycle exercise. J. Appl. Physiol. 1999,86, 1292–1300. [CrossRef]
34.
Manfredi, T.G.; Fielding, R.A.; O’Reilly, K.; Meredith, C.N.; Lee, Y.; Evans, W.J. Plasma creatine kinase actiivty
and eimd in older men. Med. Sci. Sports Exerc. 1991,23, 1028–1034. [CrossRef]
35.
Klass, M.; Baudry, S.; Duchateau, J. Voluntary activation during maximal contraction with advancing age:
A brief review. Eur. J. Appl. Physiol. 2007,100, 543–551. [CrossRef]
36.
Knight, C.A.; Kamen, G. Adaptations in muscular activation of the knee extensor muscles with strength
training in young and older adults. J. Electromyogr. Kinesiol. 2001,11, 405–412. [CrossRef]
37.
Cronin, J.B.; Hansen, K.T. Strength and power predictors of sports speed. J. Strength Cond. Res.
2005
,19,
349–357.
38.
Delaney, J.A.; Scott, T.J.; Ballard, D.A.; Duthie, G.M.; Hickmans, J.A.; Lockie, R.G.; Dascombe, B.J. Contributing
factors to change-of-direction ability in professional rugby league players. J. Strength Cond. Res.
2015
,29,
2688–2696. [CrossRef] [PubMed]
39.
Toft, A.D.; Jensen, L.B.; Bruunsgaard, H.; Ibfelt, T.; Halkjaer-Kristensen, J.; Febbraio, M.; Pedersen, B.K.
Cytokine response to eccentric exercise in young and elderly humans. Am. J. Physiol. Cell Physiol.
2002
,283,
C289–C295. [CrossRef] [PubMed]
40.
Verdijk, L.B.; Gleeson, B.G.; Jonkers, R.A.M.; Meijer, K.; Savelberg, H.H.C.M.; Dendale, P.; Van Loon, L.J.C.
Skeletal muscle hypertrophy following resistance training is accompanied by a fiber type-specific increase
in satellite cell content in elderly men. J. Gerontol. Ser. A Biol. Sci. Med. Sci.
2009
,64, 332–339. [CrossRef]
[PubMed]
41.
Friden, J.; Lieber, R.L. Eccentric exercise-induced injuries to contractile and cytoskeletal muscle fibre
components. Acta Physiol. Scand. 2001,171, 321–326. [CrossRef]
©
2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
... The duration and magnitude of the recovery process is contingent upon the specific stress and stimulus imposed by the exercise or training session [3]. resistance training, characterized by movements performed against an external resistance, can exert substantial mechanical or metabolic strain, potentially resulting in muscle damage and fatigue [4][5][6]. The extent of fatigue primarily depends on training volume and intensity [7]. ...
... conversely, higher training intensities involve loads nearing an individual's maximal strength, thereby limiting the capacity to perform a high number of repetitions [9]. High-intensity training is frequently utilized for maximal strength development, power enhancement, and neuromuscular adaptations, typically involving a lower number of repetitions [4][5][6] per set at 85-90% of one-repetition maximum [11]. The highintensity training paradigm also appears to have significant effects on subsequent neuromuscular performance. ...
Article
Full-text available
Purpose This study compared the recovery response of physical performance and cognitive function between high volume, low intensity (HV) and high intensity, low volume (HI) resistance training in resistance trained men. Methods Eight recreationally resistance trained men (27.8 ± 1.6 y; 85.5 ± 11.2 kg; 178.4 ± 8.3 cm), with at least one-year of resistance training experience (6.4 ± 3.9 y) participated in this cross-over design study. Participants were randomly assigned to either HV (6-sets of 15–20 repetitions at 60% of the participant’s one-repetition maximum (1RM), 1-min rest between sets) or HI (6-sets of 3–5 repetitions at 90% 1RM, 3-min rest between sets). Following a one-week recovery period, participants reported back to the laboratory and performed the other training session. Cognitive function (SCAT5), physical performance (isometric mid-thigh pull), and reactive agility measures were assessed at baseline, immediately-post (IP) and at 30- (30P) and 60-minutes post-exercise. Results Parametric analysis revealed no differences in peak force (p = 0.423), and the rate of force development at 200 ms (p = 0.827) and 250 ms (p = 0.797) between HI and HV. However, magnitude-based inference (MBI) analysis indicated that peak force was possibly decreased at 30P following HI and that reactive agility was likely negatively impacted at IP following HV. Friedman analysis indicated a significant decline (p = 0.035) in delayed memory during HV at IP and 30P. Conclusions Results of this study indicate that participants engaging in HV resistance training are more susceptible to experiencing performance declines in reaction time and cognitive function than HI training. These findings shed light on differences in physical and cognitive function recovery from HI and HV training programs.
... An acute consequence of RE can be EIMD, especially when the exercise comprises high-volume, high-velocity and/or eccentrically biased muscle actions [17,18]. EIMD is a transient phenomenon characterized by structural and functional consequences that are present both immediately and up to~14 days following the cessation of the initial exercise bout [19]. ...
... A decrease in the ability of the muscle to be excited at rest may be a peripheral alteration with age that increases stress on fewer muscle fibers, predisposing older individuals to greater damage [65]. In a comparison study between trained young and middle-aged males, as well as untrained middle-aged males, it was concluded that the level of damage after a squatting exercise was greatest in the order of untrained middle-age, trained middle-age, then young trained males [17]. Here, the results hint that training status may benefit older athletes in recovery, but the impacts of external therapeutic applications (i.e., nutrition and exercise) are out of the scope of this review. ...
Article
Full-text available
Understanding the intricate mechanisms governing the cellular response to resistance exercise is paramount for promoting healthy aging. This narrative review explored the age-related alterations in recovery from resistance exercise, focusing on the nuanced aspects of exercise-induced muscle damage in older adults. Due to the limited number of studies in older adults that attempt to delineate age differences in muscle discovery, we delve into the multifaceted cellular influences of chronic low-grade inflammation, modifications in the extracellular matrix, and the role of lipid mediators in shaping the recovery landscape in aging skeletal muscle. From our literature search, it is evident that aged muscle displays delayed, prolonged, and inefficient recovery. These changes can be attributed to anabolic resistance, the stiffening of the extracellular matrix, mitochondrial dysfunction, and unresolved inflammation as well as alterations in satellite cell function. Collectively, these age-related impairments may impact subsequent adaptations to resistance exercise. Insights gleaned from this exploration may inform targeted interventions aimed at enhancing the efficacy of resistance training programs tailored to the specific needs of older adults, ultimately fostering healthy aging and preserving functional independence.
... Even in resistance trained groups the differences in one-repetition maximum back squat strength and power between young (~21 years) and middle-aged (~43 years) are 27.7 and 36.4%, respectively (Fernandes et al., 2019). Given the relationship between power and activities of daily living (Hazell et al., 2007) and sports performance (Fernandes et al., 2019), the preservation of power with ageing should be prioritised. ...
... respectively (Fernandes et al., 2019). Given the relationship between power and activities of daily living (Hazell et al., 2007) and sports performance (Fernandes et al., 2019), the preservation of power with ageing should be prioritised. ...
... The associated pain can persist from the cessation of the exercise and continue in the days to follow. 1, 2 delayed onset muscle soreness (doMS), impaired muscular function, limited range of motion, and elevated intramuscular proteins are symptoms that accompany the onset of eiMd. 2,3 The etiology of eiMd is not fully understood but is proposed to be linked to the high mechanical forces ex- ...
Article
Full-text available
BACKGROUNDː According to the PRISMA guidelines, this systematic review of randomised controlled trials examined whether Panax ginseng supplementation reduces resistance to exercise-induced muscle damage (EIMD). METHODSː Web of Science, SPORTDiscus and Medline databases were searched from the 16th of December 2021 to the 18th of February 2022. Inclusion criteria were studies in humans consuming Panax ginseng that employed resistance training as the damaging muscle protocol and measured markers implicated in the aetiology of EIMD (muscle damage, muscle function and muscle soreness). The PEDro risk of bias assessment tool was used to appraise the studies critically. RESULTSː Conflicting evidence was evident in markers of muscle damage, muscle function and muscle soreness. The quality assessment suggested that all studies had some level of bias. CONCLUSIONSː From 180, six studies were included in the systematic review. The main findings suggest that Panax ginseng does not attenuate markers of EIMD following resistance training. However, research is still preliminary. Adequately powered sample sizes and well-controlled studies are warranted to clarify Panax ginseng’s efficacy.
... No strict limits on weight, height, or body mass index were considered to obtain better generalizability of the results. However, age cut-offs were established (25 to 55 years) since middle-aged individuals seem to experience greater symptoms of muscle damage and impaired recovery than young subjects [23]. Participants with cardiorespiratory conditions, musculoskeletal injuries, inflammatory disorders, or any other medical condition not compatible with extenuating exercise performance or altering the normal muscle tone (e.g., consumption of muscle relaxants) or US visualization (i.e., neuromuscular conditions) were excluded from this study. ...
Article
Full-text available
Limited evidence has verified if ultrasound imaging (US) can detect post-exercise muscle damage based on size, shape, and brightness metrics. This study aimed to analyze the correlation between creatine kinase (CK) concentration and (as a biomarker of muscle damage) changes in US gray-scale metrics after an exercise-induced muscle damage protocol. An observational study was conducted at a private university lab located in Madrid. Twenty-five untrained and asymptomatic volunteers were enrolled in this study. Baseline demographic data and body composition metrics were collected. In addition, the rectus femoris US data and CK concentration were assessed at baseline and after inducing muscle damage (24 and 48 h later). After calculating time differences for all the outcomes, the correlation between the changes observed with US and biomarkers was assessed. Significant CK concentration increases were found 24 h (p = 0.003) and 48 h (p < 0.001) after exercise. However, no significant changes in muscle size, shape, or brightness were found in any location (p > 0.05 for all). In addition, no significant associations were found between CK changes and US changes (p > 0.05 for all). Gray-scale US is not a sensitive tool for detecting muscle damage, as a protocol of exercise-induced muscle damage confirmed with CK produced no significant gray-scale US changes after 24 or 48 h. In addition, US and CK changes after 24 and 48 h were not associated with each other.
... The high eccentric forces associated with resistance exercise combined with the unaccustomed load and volume at the beginning of a training programme [10,11], mean it is well accepted that resistance exercise can induce EIMD. However, the duration and magnitude of its effects are highly variable, and depend both on the training variables [12][13][14] and individual characteristics [15][16][17], such as training intensity [12], training status [15], age [18], and sex [16]. Hence, a greater understanding of how function is affected in the days following a bout of resistance exercise is essential to inform better exercise prescription, and the formation of suitable recovery strategies for older adults. ...
Article
Full-text available
Background Resistance exercise is recommended for maintaining muscle mass and strength in older adults. However, little is known about exercise-induced muscle damage and recovery from resistance exercise in older adults. This may have implications for exercise prescription. This scoping review aimed to identify and provide a broad overview of the available literature, examine how this research has been conducted, and identify current knowledge gaps relating to exercise-induced muscle damage and recovery from resistance exercise in older adults. Methods Studies were included if they included older adults aged 65 years and over, and reported any markers of exercise-induced muscle damage after performing a bout of resistance exercise. The following electronic databases were searched using a combination of MeSH terms and free text: MEDLINE, Scopus, Embase, SPORTDiscus and Web of Science. Additionally, reference lists of identified articles were screened for eligible studies. Data were extracted from eligible studies using a standardised form. Studies were collated and are reported by emergent theme or outcomes. Results A total of 10,976 possible articles were identified and 27 original research articles were included. Findings are reported by theme; sex differences in recovery from resistance exercise, symptoms of exercise-induced muscle damage, and biological markers of muscle damage. Conclusions Despite the volume of available data, there is considerable variability in study protocols and inconsistency in findings reported. Across all measures of exercise-induced muscle damage, data in women are lacking when compared to males, and rectifying this discrepancy should be a focus of future studies. Current available data make it challenging to provide clear recommendations to those prescribing resistance exercise for older people.
... In the same sense, maximal isometric strength was also reduced by the fatigue induction protocol. After the post-fatigue retest on day 1 and day 3, strength capacity recovery cannot achieve the basal performance, which we argue resultant of the magnitude of muscle damage and the fact that an adequate recovery time was not administrated (Fernandes et al., 2019). This disruption of the regeneration process potentiates inflammation and oxidative stress, factors that negatively affect muscle strength (MacIntyre et al., 1995;Prochniewicz et al., 2008). ...
Article
Muscle fatigue can limit performance both in sports and daily life activities. Consecutive days of exercise without a proper recovery time may elicit cumulative fatigue. Although it has been speculated that skin temperature could serve as an indirect indicator of exercise-induced adaptations, it is unclear if skin temperature measured by infrared thermography (IRT) could be an outcome related to the effects of cumulative fatigue. In this study, we recruited 21 untrained women and induced cumulative fatigue in biceps brachii over two consecutive days of exercise. We measured delayed onset muscle soreness (DOMS, using a numeric rate scale), maximal strength (using a dynamometer), and skin temperature (using IRT) in exercise and non-exercise muscles. Cumulative fatigue reduced muscle strength and increased DOMS. Skin temperature in the arm submitted to cumulative fatigue was higher for minimum and mean temperature, being asymmetrical in relation to the control arm. We also observed that the variations in the minimum and mean temperatures correlated with the strength losses. In summary, skin temperature measured by IRT seems promising to help detect cumulative fatigue in untrained women, being useful to explain strength losses. Future studies should provide additional evidence for the potential applications not only in trained participants but also in patients that may not be able to report outcomes of scales or precisely report DOMS.
Article
Traumatic musculoskeletal injuries that lead to volumetric muscle loss (VML) are challenged by irreparable soft tissue damage, impaired regenerative ability, and reduced muscle function. Regenerative rehabilitation strategies involving the pairing...
Article
Eccentric muscle contractions can cause structural damage to muscle cells resulting in temporarily decreased muscle force production and soreness. Prior work indicates pasture-raised dairy products from grass-fed cows have greater anti-inflammatory and antioxidant properties compared to grain-fed counterparts. However, limited research has evaluated the utility of whey protein from pasture-raised, grass-fed cows to enhance recovery compared to whey protein from non-grass-fed cows. Therefore, using a randomized, placebo-controlled design, we compared the effect of whey protein from pasture-raised, grass-fed cows (PRWP) to conventional whey protein (CWP) supplementation on indirect markers of muscle damage in response to eccentric exercise-induced muscle damage (EIMD) in resistance-trained individuals. Thirty-nine subjects (PRWP, n = 14; CWP, n = 12) completed an eccentric squat protocol to induce EIMD with measurements performed at 24, 48, and 72 h of recovery. Dependent variables included: delayed onset muscle soreness (DOMS), urinary titin, maximal isometric voluntary contraction (MIVC), potentiated quadriceps twitch force, countermovement jump (CMJ), and barbell back squat velocity (BBSV). Between-condition comparisons did not reveal any significant differences (p ≤ 0.05) in markers of EIMD via DOMS, urinary titin, MIVC, potentiated quadriceps twitch force, CMJ, or BBSV. In conclusion, neither PRWP nor CWP attenuate indirect markers of muscle damage and soreness following eccentric exercise in resistance-trained individuals.
Article
Purpose; This meta-analysis aimed to 1) provide a comparison of peak changes in indirect markers of EIMD in youths versus adults and 2) determine if the involved limb moderated this effect. Method; Studies were eligible for inclusion if they 1) provided a human youth versus adult comparison, 2) provided data on muscle strength, soreness or creatine kinase (CK) markers beyond ≥ 24 hours, 3) did not provide a recovery treatment. Effect sizes (ES) were presented alongside 95% confidence intervals. Results; EIMD exhibited larger effects on adults than in youths for muscle strength (ES=-2.01; P<0.001), muscle soreness (ES=-1.52; P<0.001) and CK (ES=-1.98; P<0.001). The random effects meta-regression examined the effects of upper- and lower-limb exercise in youths and adults was significant for muscle soreness (coefficient estimate =1.11; P< 0.001) but not muscle strength or CK (P>0.05). As such, the between-group effects for muscle soreness (ES=-2.10 versus -1.03; P<0.05) were greater in the upper- than lower-limb. Conclusion; The magnitude of EIMD in youths is substantially less than their adult counterparts, and this effect is greater in upper- than lower-limbs for muscle soreness. These findings help guide practitioners who may be concerned about the potential impact of EIMD when training youth athletes.
Article
Full-text available
The purpose of this study was to compare the effects of a bout of high-volume isokinetic resistance exercise (HVP) on lower-body strength and markers of inflammation and muscle damage during recovery between young and middle-aged men. Nineteen recreationally-trained men were classified as either a young adult (YA: 21.8 ± 2.0 y; 90.7 ± 11.6 kg) or middle-aged adult (MA: 47.0 ± 4.4 y; 96.0 ± 21.5 kg) group. The HVP consisted of 8 sets of 10 repetitions, with one minute of rest between each set, performed on an isokinetic dynamometer at 60°·sec. Maximal voluntary isometric contractions (MVIC) and isokinetic peak (PKT) and average (AVGT) torque (measured at 240° and 60°·sec) were assessed at baseline (BL), immediately-post (IP), 120-min (120P), 24-hr (24H) and 48-hr (48H) following HVP. Blood was obtained at BL, IP, 30-min, 60-min, 120-min, 24H and 48H following HVP to assess muscle damage and inflammation. All performance data were analyzed using repeated-measures ANCOVA, while all inflammatory and muscle damage markers were analyzed using a two-way (time x group) repeated-measures ANOVA. Results revealed no between-group differences for PKT, AVGT, or rate of torque development at 200ms (RTD200). No between-group differences in myoglobin, creatine kinase, C-reactive protein, or interleukin-6 were observed. Although baseline differences in muscle performance were observed between YA and MA, no between group differences were noted in performance recovery measures from high-volume isokinetic exercise in recreationally-trained men. These results also indicate that the inflammatory and muscle damage response from high-volume isokinetic exercise is similar between recreationally-trained, young and middle-aged adult men.
Article
Full-text available
This study examined the load-velocity and load-power relationships among 20 young (age 21.0 ± 1.6 y) and 20 middle-aged (age 42.6 ± 6.7 y) resistance trained males. Participants performed three repetitions of bench press, squat and bent-over-row across a range of loads corresponding to 20 to 80% of one repetition maximum (1RM). Analysis revealed effects (P < 0.05) of group and load x group on barbell velocity for all three exercises, and interaction effects on power for squat and bent-over-row (P < 0.05). For bench press and bent-over-row, the young group produced higher barbell velocities, with the magnitude of the differences decreasing as load increased (ES; effect size 0.0 to 1.7 and 1.0 to 2.0, respectively). Squat velocity was higher in the young group than the middle-aged group (ES 1.0 to 1.7) across all loads, as was power for each exercise (ES 1.0 to 2.3). For all three exercises, both velocity and 1RM were correlated with optimal power in the middle-aged group (r = .613 to .825, P < 0.05), but only 1RM was correlated with optimal power (r = .708 to .867, P < 0.05) in the young group. These findings indicate that despite their resistance training, middle-aged males were unable to achieve velocities at low external loads and power outputs as high as the young males across a range of external resistances. Moreover, the strong correlations between 1RM and velocity with optimal power suggest that middle-aged males would benefit from training methods which maximise these adaptations.
Article
Full-text available
BACKGROUND: The FitroDyne has been used to assess muscle function but its reproducibility has not been determined during traditional multi-jointed resistance exercises. OBJECTIVE: To assess the intra- and inter-day reproducibility of the FitroDyne during traditional resistance exercises. METHODS: Fourteen resistance trained males completed a one repetition maximum (1RM) and three repetitions of bench press, squat and bent-over-row in 10% increments (from 20 to 80%). Replica trials were completed two and 48 hours later. The FitroDyne rotary encoder measured barbell velocity during each repetition from which power output was calculated. RESULTS: For all loads and exercises the intra-day typical error (TE) for peak and mean power, and velocity, respectively, during bench press (8.2-53 W and 2.2-6.9 cm s-1), squat (13.3-55.6W and 2.4-7.4 cm s-1), and bent-over-row (14.5-62.8W and 4-10.5 cm s-1) identified only moderate changes. Bench press yielded poor intra-day reproducibility at 80% 1RM only (CV% = 12.2-17.1), whereas squat and bent-over-row across all loads for peak and mean power and velocity displayed better reproducibility CV% = 2.4-9.0). Inter-day, the TE detected moderate changes for peak and mean power and velocity for all three exercises. Inter-day reproducibility was comparable to intra-day, though improved for bench press 80% 1RM (CV% = 6.1-8.6). CONCLUSION: These data support the use of the FitroDyne at submaximal loads for monitoring moderate changes in muscle function both intra- and inter-day.
Article
Full-text available
Rugby league is an intermittent team sport in which players are regularly required to accelerate, decelerate, and change direction rapidly. This study aimed to determine the contributing factors to change-of-direction (COD) ability in professional rugby league players, and secondly, to validate the physical and physiological components of a previously proposed COD ability predictor model. Thirty-one male professional rugby league players (24.3 ± 4.4 yr; 1.83 ± 0.06 m; 98.1 ± 9.8 kg) were assessed for anthropometry, linear speed, various leg muscle qualities, and COD ability. COD ability was assessed for both the dominant (D) and non-dominant (ND) legs using the 505 test. Stepwise multiple regression analyses determined the combined effect of the physical and physiological variables on COD ability. Maximal linear speed (SpMax) and relative squat strength (Squat:BM) explained 61% of the variance in 505-D performance, while measures of mass, unilateral and bilateral power contributed 67% to 505-ND performance. These results suggest that the 505-ND task was heavily dependent on relative strength and power, while the 505-D task was best predicted by linear sprint speed. Secondly, the physical component of the COD predictor model demonstrated poor correlations (r = -0.1 to -0.5) between absolute strength and power measures and COD ability. When made relative to body mass, strength and power measures and COD ability shared stronger relationships (r = -0.3 to -0.7). COD ability in professional rugby league players would be best improved through increases in an athlete's strength and power, while also maintaining lean muscle mass.
Article
Full-text available
The objective of this study is to understand the effectiveness of foam rolling (FR) as a recovery tool after exercise-induced muscle damage, analyzing thigh girth, muscle soreness, range of motion (ROM), evoked and voluntary contractile properties, vertical jump, perceived pain while FR, and force placed on the foam roller. Twenty male subjects (≥3 yr of strength training experience) were randomly assigned into the control (n = 10) or FR (n = 10) group. All the subjects followed the same testing protocol. The subjects participated in five testing sessions: 1) orientation and one-repetition maximum back squat, 2) pretest measurements, 10 × 10 squat protocol, and POST-0 (posttest 0) measurements, along with measurements at 3) POST-24, 4) POST-48, and 5) POST-72. The only between-group difference was that the FR group performed a 20-min FR exercise protocol at the end of each testing session (POST-0, POST-24, and POST-48). FR substantially reduced muscle soreness at all time points while substantially improving ROM. FR negatively affected evoked contractile properties with the exception of half relaxation time and electromechanical delay (EMD), with FR substantially improving EMD. Voluntary contractile properties showed no substantial between-group differences for all measurements besides voluntary muscle activation and vertical jump, with FR substantially improving muscle activation at all time points and vertical jump at POST-48. When performing the five FR exercises, measurements of the subjects' force placed on the foam roller and perceived pain while FR ranged between 26 and 46 kg (32%-55% body weight) and 2.5 and 7.5 points, respectively. The most important findings of the present study were that FR was beneficial in attenuating muscle soreness while improving vertical jump height, muscle activation, and passive and dynamic ROM in comparison with control. FR negatively affected several evoked contractile properties of the muscle, except for half relaxation time and EMD, indicating that FR benefits are primarily accrued through neural responses and connective tissue.
Article
Skeletal muscle adapts to exercise-induced damage by orchestrating several, but still poorly understood mechanisms that endow protection from subsequent damage. Known widely as the repeated bout effect, we propose that neural adaptations, alterations to muscle mechanical properties, structural remodeling of the extracellular matrix, and biochemical signaling work in concert to coordinate the protective adaptation.
Article
Purpose: The best sprint performances are usually reached between the ages of 20 and 30; however even in well-trained individuals, performance continues to decrease with age. While this inevitable decrease in performance has been related to reductions in muscular force, velocity and power capabilities, these measures have not been assessed in the specific context of sprinting. The aim of this study was to investigate the mechanical outputs of sprinting acceleration among Masters sprinters to better understand the mechanical underpinnings of the age-related decrease in sprint performance. Methods: The study took place during an international Masters competition, with testing performed at the end of the warm-up for official sprint races. Horizontal ground reaction force, velocity, mechanical power outputs and mechanical effectiveness of force application were estimated from running velocity-time data during a 30-m sprint acceleration in twenty-seven male sprinters (39 to 96 yrs). Data were presented in the form of age-related changes and compared to elite young sprinters data. Results: Maximal force, velocity and power outputs decreased linearly with age (all r>0.84; P<0.001), at a rate of ~1% per year. Maximal power of the oldest subject tested was about one ninth of that of younger world-class sprinters (3.57 vs. 32.1 W·kg). While the maximal effectiveness of horizontal force application also decreased with age, its decrease with increasing velocity within the sprint acceleration was not age-dependent. Conclusions: In addition to lower neuromuscular force, velocity and power outputs, Master sprinters had a comparatively lower effectiveness of force application, especially at the beginning of the sprint.
Article
We investigated the responses of indirect markers of exercise-induced muscle damage (EIMD) among a large number of young men (N=286) stratified in clusters based on the largest decrease in maximal voluntary contraction torque (MVC) after an unaccustomed maximal eccentric exercise bout of the elbow flexors. Changes in MVC, muscle soreness (SOR), creatine kinase (CK) activity, range of motion (ROM) and upper-arm circumference (CIR) before and for several days after exercise were compared between 3 clusters established based on MVC decrease (low, moderate, and high responders; LR, MR and HR). Participants were allocated to LR (n=61), MR (n=152) and HR (n=73) clusters, which depicted significantly different cluster centers of 82%, 61% and 42% of baseline MVC, respectively. Once stratified by MVC decrease, all muscle damage markers were significantly different between clusters following the same pattern: small changes for LR, larger changes for MR, and the largest changes for HR. Stratification of individuals based on the magnitude of MVC decrease post-exercise greatly increases the precision in estimating changes in EIMD by proxy markers such as SOR, CK activity, ROM and CIR. This indicates that the most commonly used markers are valid and MVC orchestrates their responses, consolidating the role of MVC as the best EIMD indirect marker. © Georg Thieme Verlag KG Stuttgart · New York.
Article
The response of skeletal muscle to unaccustomed eccentric exercise has been studied widely, yet it is incompletely understood. This review is intended to provide an up-to-date overview of our understanding of how skeletal muscle responds to eccentric actions, with particular emphasis on the underlying molecular and cellular mechanisms of damage and recovery. Our review begins by addressing the question of whether eccentric actions result in physical damage to muscle fibers and/or connective tissue. We next review the symptomatic manifestations of eccentric exercise (i.e. indirect damage markers, such as delayed onset muscle soreness), with emphasis on their relatively poorly understood molecular underpinnings. We then highlight factors that potentially modify the muscle damage response following eccentric exercise. Finally, we explore the utility of using eccentric training to improve muscle function in populations of healthy and aging individuals, as well as those living with neuromuscular disorders. © 2013 Wiley Periodicals, Inc.