Subjects and Study Characteristics
16 papers met the meta-analysis inclusion criteria and analyzed TMG for muscle fatigue after an acute exercise in 393 healthy participants. 8 papers studied elite athletes, 7 studied amateurs and active individuals, and 1 studied both amateur and elite athletes. Regarding the study design, 9 were single-group pre-posttest studies, 6 were crossover studies, and 1 was a randomized controlled trial (Table 2).
Table 2
Study
(Year of Publication)
|
Study
Design
|
Participants
|
Age
(Year ± SD)
|
Gender
|
Training Level
|
Exercise Protocol
|
Measure
Muscle
|
TMG Variables
|
Barcala-Furelos
(2020)
|
single group pre-posttest
|
20
|
24.0 ± 4.9
|
16Male
4Female
|
active
|
swimming / 100 m with fins to the victim, and towing the victim 100 m back (victim: height, 160–190 cm; weight, 60–90 kg)
|
RF
|
Dm, Tc
|
Beato
(2019)
|
randomized controlled trial
|
32
|
21 ± 3
|
Male
|
amateur
|
train / 15 min workout programs
|
VL, VM, RF
|
Dm, Tc, Td, Vc10, Vc90
|
Berzosa
(2020)
|
Crossover
|
10
|
27 ± 1.5
|
Male
|
active
|
squat / each exercise session consisted of 4 sets of 7 repetitions interspersed by 2 min between-set rest intervals.
|
RF, BF
|
Dm, Tc
|
Calderón-Pellegrino (2020)
|
single group pre-posttest
|
32
|
23 ± 5
|
Male
|
elite
|
RSA / seven repeated sprints of 30 m, with 20 s of active recovery between
|
RF, BF
|
Dm, Tc, Td
|
García-García
(2020)
|
single group pre-posttest
|
48
|
20.2 ± 2.3
|
Male
|
elite
|
maximal incremental cycling test / increased 20 W·min− 1, frequency of 80–90 rev·min− 1, reached an average of 393.8 ± 41.6 W (5.8 ± 0.4 Wpeak·kg− 1) test duration was 1228 ± 120 s
|
VL, RF, BF
|
Dm, Tc, Td, Ts, Vrd
|
García-Unanue
(2020)
|
single group pre-posttest
|
33
|
23.4 ± 4.4
|
Male
|
elite / amateur
|
RSA / seven repeated sprints of 30 m, with 20 s of active recovery between
|
RF, BF
|
Dm, Tc, Td, Ts, Tr
|
López-Fernández
(2017)
|
Crossover
|
16
|
22.2 ± 3.4
|
Male
|
amateur
|
soccer simulation protocol / 3 bouts of the SSP, Each bout last 16 min with 3 min of rest between bouts.
|
RF, BF
|
Dm, Tc, Td, Ts, Tr
|
Martín-San Agustín
(2020)
|
single group pre-posttest
|
35
|
22 ± 2
|
16Male
19Female
|
active
|
MVIC / measure 3 MVIC, and 60 s fatiguing isometric
contraction at 70% MVC
|
VL, VM, RF
|
Dm, Tc, Vc10, Vc90
|
Pereira
(2020)
|
Crossover
|
14
|
21.8 ± 2.6
|
Male
|
elite
|
train / 40–50 min workout programs
|
RF, BF
|
Vc90
|
Rodríguez-Matoso
(2015)
|
single group pre-posttest
|
11
|
28.2 ± 2.9
|
Male
|
elite
|
surfing / wave size 1–1½ m wave length 6–9 s wave direction right distance paddling 40–50 m, heat length 20 min
|
VL, VM, RF, BF, ST
|
Dm, Ts, Tr, Vrn
|
Rojas-Barrionuevo
(2017)
|
Crossover
|
14
|
20.7 ± 3.1
|
Male
|
elite
|
forward tucked somersaults / 12 sets of 6 repetitions of forward tucked somersaults, a rest period of 2 min between sets, 5 s between repetitions was implemented
|
VL, VM, RF, BF, GM
|
Vrn
|
Rojas-Valverde
(2020)
|
Crossover
|
20
|
20.4 ± 3.2
|
Male
|
active
|
running / 30 min running
|
RF, BF
|
Dm, Tc
|
Sánchez-Sánchez
(2018)
|
single group pre-posttest
|
20
|
25.5 ± 6.1
|
Male
|
elite
|
RSA / seven repeated sprints of 30 m, with 20 s of active recovery between
|
RF, BF
|
Dm, Tc, Td, Ts
|
Sánchez-Sánchez
(2019)
|
single group pre-posttest
|
62
|
14.6 ± 2.0
|
Male
Female
|
elite
|
RSA / seven repeated sprints of 30 m, with 20 s of active recovery between
|
RF, BF
|
Dm, Tc, Td
|
Santana
(2018)
|
single group pre-posttest
|
11
|
20.8 ± 3.2
|
Male
|
elite
|
forward tucked somersaults / 12 sets of 6 repetitions of forward tucked somersaults, A rest period of 2 min between sets, 5 s between repetitions was implemented
|
VL, VM, RF, BF, GM
|
Dm, Tc, Td, Vrn
|
Ubago Guisado
(2017)
|
Crossover
|
15
|
23.4 ± 3.4
|
Female
|
amateur
|
modified RSA / consisted of six sprints of 40 m (20 + 20 m) with 20 s of passive recovery
|
RF, BF
|
Dm, Tc, Td, Tr
|
Caption RSA repeated sprint ability, MVIC maximal voluntary isometric contraction BF biceps femoris, RF rectus femoris, VL vastus lateralis, VM vastus medialis, ST semitendinosus, GM medial gastrocnemius Dm maximum displacement, Tc contraction time, Td delay time, Ts sustain time, Tr relaxation time, Vrd radial displacement velocity, Vrn normalized response speed, Vc10 mean velocity until 10% Dm, Vc90 mean velocity until 90% Dm
Tensiomyography
All 16 studies analyzed RF, 13 studies measured BF, 6 measured VL, 5 measured VM, 1 measured ST, and 2 measured GM. Regarding TMG variables, 14 studies measured Dm, 13 measured Tc, 9 measured Td, 3 measured Vc90, 1 measured Vc10, 5 measured Ts, 4 measured Tr, 3 measured Vrn, and 1 measured Vrd. Papers that presented Dm, Tc, and Td together used the Vc90 calculation formula to convert them into Vc90 (Table 2).
Exercise Protocols
Of the 16 studies, 4 used RSA, 1 used MICT, 1 used MVIC, 3 used weight training, 3 used running, 1 used swimming, 2 used forward-tucked somersaults, and 1 used surfing to induce acute muscle fatigue (Table 2).
Methodological Bias Assessment
The mean CAT score and SD was 9.5 ± 1.5 (range 6–11), 14 papers had a low risk of bias and good methodological quality, 1 had a moderate risk of bias and average methodological quality, and 1 had a high risk of bias and low methodological quality (Table 3).
Table 3
Quility and risk of bias assessment of the included validity studies, utilized with the critical appraisal tool (CAT)
Author
(Year of Publication)
|
Q1
|
Q2
|
Q3
|
Q4
|
Q5
|
Q6
|
Q7
|
Q8
|
Q9
|
Q10
|
Q11
|
Q12
|
Q13
|
Total
|
Risk of bias
|
Barcala-Furelos (2020)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
N
|
Y
|
N
|
N
|
Y
|
Y
|
Y
|
Y
|
8/11
|
Low
|
Beato (2019)
|
Y
|
N
|
Y
|
N/A
|
N/A
|
Y
|
N
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
9/11
|
Low
|
Berzosa (2020)
|
Y
|
N
|
Y
|
N/A
|
N/A
|
N
|
Y
|
N
|
N
|
Y
|
Y
|
Y
|
Y
|
7/11
|
Moderate
|
Calderon-Pellegrino (2020)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
N
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
10/11
|
Low
|
Garcia-Garcia (2020)
|
Y
|
N
|
Y
|
N/A
|
N/A
|
Y
|
N
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
9/11
|
Low
|
Garcia-Unanue (2020)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
N
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
10/11
|
Low
|
Lopez-Fernandez (2017)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
11/11
|
Low
|
Martin-San Agustin (2020)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
11/11
|
Low
|
Pereira (2020)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
11/11
|
Low
|
Rodriguez-Matoso (2015)
|
Y
|
N
|
N
|
N/A
|
N/A
|
Y
|
N
|
Y
|
Y
|
N
|
N
|
Y
|
Y
|
6/11
|
High
|
Rojas-Barrionuevo (2017)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
Y
|
N
|
Y
|
Y
|
Y
|
Y
|
Y
|
10/11
|
Low
|
Rojas-Valverde (2020)
|
Y
|
N
|
Y
|
N/A
|
N/A
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
10/11
|
Low
|
Sanchez-Sanchez (2018)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
N
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
10/11
|
Low
|
Sanchez-Sanchez (2019)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
11/11
|
Low
|
Santana (2018)
|
Y
|
N
|
Y
|
N/A
|
N/A
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
Y
|
10/11
|
Low
|
Ubago (2017)
|
Y
|
Y
|
Y
|
N/A
|
N/A
|
Y
|
N
|
N
|
Y
|
Y
|
Y
|
Y
|
Y
|
9/11
|
Low
|
Caption Q question, Y yes, N no, N/A not applicable
Meta-analysis Results
Heterogeneity Evaluation and publication bias
The overall heterogeneity was I2 = 35.77% ± 30.30(SD). It was either moderate or high. Some studies had significant Q-value, in the RF Dm that showed elite athletes I2: 55.47% and overall I2 = 52.67%. The BF Vc90 showed elite athletes I2 = 60.71% and overall I2 = 55.15%. The RF Vc90 showed an average person I2 = 85.01%, elite athletes I2 = 80.11%, and overall I2 = 82.28%. However, there I2 were insignificantly heterogeneous. And all analysis were not publication bias
Comparison Between Elite Athletes and Average Persons
The random effects meta-analysis model analyzed the differences in the TMG variables that measured BF and RF muscle fatigue after an acute exercise.
The ES of BF Dm was insignificant for the average person (Hedges’s g = 0.007, 95% CI = -0.189 to 0.202, p = 0.946, I2 = 0.00%), whereas the elite athletes showed a small but significant decrease (Hedges’s g = -0.386, 95% CI = -0.566 to -0.207, p = 0.000, I2 = 9.50%). The overall effect also showed a small but significant decrease (Hedges’s g = -0.207, 95% CI = -0.339 to -0.075, p = 0.002, I2 = 24.51%). And the ES of RF Dm showed a small but significant decrease for the average person (Hedges’s g = -0.298, 95% CI = -0.518 to -0.078, p = 0.008, I2 = 34.94%), whereas the change was insignificant in elite athletes (Hedges’s g = 0.132, 95% CI = -0.101 to 0.366, p = 0.266, I2 = 55.47%). The overall effect was statistically insignificant (Hedges’s g = -0.095, 95% CI = -0.256 to 0.065, p = 0.242, I2 = 52.67%) (Fig. 2).
The ES of BF Tc change was insignificant in the average person (Hedges’s g = 0.014, 95% CI = -0.180 to 0.209, p = 0.885, I2 = 0.00%), but showed a very small but significant decrease in elite athletes (Hedges’s g = -0.164, 95% CI = -0.316 to -0.013, p = 0.033, I2 = 0.00%). However, the overall effect was statistically insignificant (Hedges’s g = -0.097, 95% CI = -0.216 to 0.022, p = 0.111, I2 = 0.00%). And the ES of RF Tc change was insignificant in the average person (Hedges’s g = -0.144, 95% CI = -0.304 to 0.016, p = 0.078, I2 = 0.00%), yet showed a very small but significant decrease in elite athlete (Hedges’s g = -0.172, 95% CI = -0.336 to -0.007, p = 0.041, I2 = 8.51%). The overall effect also showed a very small but significant decrease (Hedges’s g = -0.157, 95% CI = -0.272 to -0.043, p = 0.007, I2 = 0.00%) (Fig. 3).
The ES of BF Vc90 change was insignificant in the average person (Hedges’s g = -0.159, 95% CI = -0.498 to 0.181, p = 0.359, I2 = 15.20%), but showed a small but significant decrease in elite athletes (Hedges’s g = -0.387, 95% CI = -0.663 to -0.111, p = 0.006, I2 = 60.71%). The overall effect also showed a small but significant decrease (Hedges’s g = -0.296, 95% CI = -0.510 to -0.082, p = 0.007, I2 = 55.15%). And the ES of RF Vc90 change was insignificant for the average person (Hedges’s g = 0.335, 95% CI = -0.295 to 0.965, p = 0.298, I2 = 85.01%), elite athletes (Hedges’s g = 0.115, 95% CI = -0.253 to 0.484, p = 0.540, I2 = 80.11%), and in the overall effect (Hedges’s g = 0.171, 95% CI = -0.147 to 0.489, p = 0.292, I2 = 82.28%) (Fig. 4).
Thus, in BF a substantial decreasing trend in all variables was observed in the elite athletes, with a substantial decreasing trend in the overall effects of Dm and Vc90. Whereas, in RF a substantial decreasing trend was found for Tc in the elite athletes, while Dm was substantial decreasing trend in the average person.