Effects of flywheel training on strength-related variables in female populations. A
1
systematic review
2
3
Javier Raya-González
1
, Kevin L. de Keijzer
2
, Chris Bishop
3
, Marco Beato
2
4
5
1. Faculty of Health Sciences, Universidad Isabel I, Burgos, Spain.
6
2. School of Health and Sports Science, University of Suffolk, Ipswich, United Kingdom.
7
3. Faculty of Science and Technology, London Sport Institute, Middlesex University, London,
8
United Kingdom.
9
10
Corresponding author. Marco Beato, School of Health and Sports Science, University of
11
Suffolk, Ipswich, United Kingdom; M.Beato@uos.ac.uk
12
13
Manuscript was submitted as “PREPRINT” paper into SportRxiv on the 09/06/2020.
14
This paper is currently in review in a peer-reviewed journal.
15
All co-authors are aware of, and have agreed to, submission and all named authors have been
16
notified upon upload.
17
Citation: APA
18
González, J. R., de Keijzer, K.L., Bishop, C., & Beato, M. (n.d.). Effects of flywheel training
19
on strength-related variables in female populations. A systematic review. Retrieved from
20
osf.io/preprints/sportrxiv/b75z9
21
22
Preprint DOI SportRxiv: 10.31236/osf.io/b75z9
23
24
ABSTRACT
25
Background: This study aimed to evaluate the effect of flywheel training on female
26
populations, report practical recommendations for practitioners based on the current available
27
evidence, underline the limitations of current literature, and establish future research directions.
28
Methods: Studies were searched through the electronic databases (PubMed, SPORTDiscus,
29
and Web of Science) following the preferred reporting items for systematic reviews and meta-
30
analysis statement guidelines.
31
Results: The methodological quality of the 7 studies included in this review ranged from 10 to
32
19 points (good to excellent), with an average score of 14-points (good). These studies were
33
carried out between 2004 and 2019 and comprised a total of 100 female participants. The
34
training duration ranged from 5 weeks to 24 weeks, with volume ranging from 1 to 4 sets and
35
7 to 12 repetitions, and frequency ranged from 1 to 3 times a week.
36
Discussion: The literature suggests that flywheel training is a safe and time effective strategy
37
to obtain lower limb performance enhancements and positive muscle morphological
38
adaptations with elderly and young females. The present literature, although limited, supports
39
the use flywheel training for the prevention of falls and the enhancement of physical
40
capabilities in young and elderly female populations. Nonetheless, a lack of clarity still exists
41
regarding appropriate flywheel training volume, frequency, and intensity. Further high-quality
42
investigation into this topic is warranted to establish clear guidelines about the use of flywheel
43
training methodologies with female populations.
44
KEYWORDS: isoinertial, women, eccentric, performance, health
45
46
KEY POINTS
47
- Flywheel training is a safe and time effective strategy to obtain lower limb performance
48
enhancements and positive muscle morphological adaptations with elderly and young females.
49
- The present literature, although limited, supports the use flywheel training for the prevention
50
of falls and the enhancement of physical capabilities in young and elderly female populations.
51
-A lack of clarity still exists regarding appropriate flywheel training volume, frequency, and
52
intensity.
53
-Further high-quality investigation into this topic is warranted to establish clear guidelines
54
about the use of flywheel training methodologies with female populations.
55
56
INTRODUCTION
57
The importance of strength training is widely recognized as being a key staple in training
58
programmes for the enhancement of athletic performance [1,2], with the relationship between
59
strength and jump [3,4], linear speed [3,5], and change of direction (COD) speed [2,6,7] evident
60
throughout the literature. In addition, strength training has also been shown to mitigate the
61
potential risk of non-contact injuries [8,9] in athlete populations as well as to improve physical
62
parameters and promote beneficial muscle adaptations in healthy sedentary and physically
63
active individuals [10]; thus, its inclusion in athlete (performance), sedentary and physically
64
active individuals training programmes is undeniable. Numerous methods have been proven to
65
be effective for the development of strength in various populations, such as: bilateral lower
66
limb movements (e.g. back squats and deadlifts) [11,12], unilateral lower body training (e.g.
67
step ups and rear foot elevated split squats [11,13] and more recently, flywheel (isoinertial)
68
training [14–18], where a wide variety of exercises can be performed. Several studies have
69
described the advantages of flywheel training and attempted to explain its physiological
70
mechanisms, and outcomes for performance and health [10,19].
71
72
Flywheel exercise has been reported to be a valid strategy for obtaining both acute performance
73
enhancement and chronic adaptations [15,20]. Flywheel training typically involves similar
74
movement patterns to traditional resistance training (squats or lunges), although this depends
75
upon the desired goal of the programme [18,21–24]. The morphological and strength benefits
76
of flywheel training likely derive from the combination of both concentric-eccentric
77
contractions [19]; however, the main peculiarity of this training methodology is the overload
78
generated during the eccentric portion of the exercise [20,25]. The benefits deriving from
79
eccentric exercise have been largely reported in the literature, including preferential
80
recruitment of high threshold motor units, higher force output production and lower energy
81
expenditure compared with both isometric and concentric muscle contractions [26,27]. For the
82
aforementioned reasons, flywheel training may be particularly effective for improving physical
83
adaptations. From a performance prospective, Nunez et al. [28] compared the effects of a 6-
84
week flywheel training programme consisting of either squats or lunges on countermovement
85
jump (CMJ) and COD speed, in 27 young active male subjects. Both programmes showed
86
small improvements in CMJ height (effect size [Cohen’s d] = 0.28-0.42) and moderate
87
improvements in COD time (d = 0.70-0.75). Similar results in jump and COD speed were noted
88
by Gonzalo-Skok et al. [14] who used bilateral squats and multidirectional COD movements
89
(in the form of flywheel training), on 48 team-sport athletes. Small to moderate improvements
90
were shown in COD performance (d = 0.35-0.61), small improvements in bilateral and
91
unilateral CMJ (d = 0.27-0.42) and small to large improvements in lateral and horizontal
92
jumping (d = 0.43-0.87). Finally, Madruga-Parera et al. [16] compared the effects of an 8-week
93
flywheel training vs. cable resistance training programmes, using 34 male youth handball
94
athletes. Both training interventions showed significant (p < 0.001) improvements in COD and
95
repeated COD performance; however, the flywheel training intervention was superior for
96
repeated COD improvements (d = -1.35 vs. -0.22). From an health prospective, Norrbrand et
97
al. [29] reported that robust muscular adaptations in cross-sectional area (CSA) and maximal
98
voluntary contractions following a 5-week flywheel training programme (2-3 times a week)
99
consisting of concentric–eccentric knee extensions in healthy men. Bruseghini et al. [30]
100
reported significant increments in CSA (4%) and isokinetic strength (10%) following an 8
101
week flywheel 4 x 7 maximal bilateral knee extension/flexion training protocol. Additionally,
102
Tesch et al., [10] reported that flywheel training is a valid method of treating age-induced
103
skeletal muscle atrophy, and in particular that this resistance training appears to be more
104
effective than traditional weight training.
105
106
Collectively, these studies highlight that training with flywheel technology may elicit small to
107
large improvements in measures of athletic performance and promote both CSA and strength
108
increments in sedentary and healthy men [20,29–31]. However, it must be acknowledged that
109
the samples used in the aforementioned studies were, and typically are, male. Conversely, the
110
volume of literature pertaining to flywheel training studies using female populations is scarce,
111
with a significant amount of research necessary to understand the benefits of this training
112
methodology with females. Therefore, the aims of the present systematic review were to: 1)
113
evaluate and summarize the effect of flywheel training on females, 2) report practical
114
recommendations for practitioners based on the current available evidence on how flywheel
115
training can offer clinical and sport advantages in applied settings, 3) underline the current
116
limitations of the literature and establish future research directions.
117
118
2. MATERIALS AND METHODS
119
The present review was carried out following the recommendations and criteria established in
120
the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement
121
guidelines [32].
122
123
2.1. Search Strategy
124
For this systematic review, potential studies were identified in PubMed/MEDLINE,
125
SPORTDiscus, and Web of Science (including all Web of Science Core Collection: Citation
126
Indexes) databases. The search syntax included the following keywords coupled with Boolean
127
operators: (“flywheel” AND “female”) OR (“isoinertial” AND “female”). A year restriction
128
was applied for this search (i.e., studies published between 1990 and 2020). In addition, a
129
secondary search was performed based on the screening of the reference lists of these studies
130
and the studies that cited the included studies through Google Scholar. Two authors (KDK and
131
MB) independently screened the title and abstract of each reference to locate potentially
132
relevant studies and reviewed them in detail to identify articles that met the inclusion criteria.
133
Following both searches, studies were uploaded to reference manager software (Zotero, version
134
5.0.85, Corporation for Digital Scholarship, Vienna, USA). All articles were reviewed and
135
screened for duplicates. Based on the study title, author, year of publication, DOI, ISBN fields,
136
duplicates were identified and merged using the “Duplicate Items” function.
137
138
2.2. Inclusion Criteria
139
The studies included in the present review had to fulfil the following inclusion criteria: (a) the
140
sample must be composed by female participants, (b) studies that analysed the effect of
141
flywheel or isoinertial training of different groups (e.g. flywheel vs. control) were reported in
142
a differentiated way (i.e., specific data of each group), (c) studies needed to report flywheel or
143
isoinertial training or provide sufficient data to calculate it through standardized equations, and
144
(d) studies had to be the full-text published in a peer-reviewed journal. In addition, conference
145
abstracts, letters to the editor, errata, narrative reviews, systematic reviews, meta-analyses or
146
invited commentaries and studies that were not written in English were excluded.
147
148
2.3. Study Coding and Data extraction
149
The following moderator variables were extracted from the included studies: (a) authors, year
150
of publication and study design, (b) sample characteristics (including sample size, age, and
151
status) (c) follow-up duration and (d) trial data (duration, volume and inertia (intensity)
152
utilised) (e) participants did not use supplements or ergogenic aids during the intervention
153
period.
154
155
2.4. Methodological Quality Assessment
156
While the methodological quality analysis of studies is often conducted using either: (i) the
157
PEDro scale; (ii) the Delphi scale; or (iii) the Cochrane scale, previous research has illustrated
158
that non-healthcare studies (e.g. strength and conditioning) typically score low using these
159
methodological scales. Subsequently, using methods reported by Brughelli et al. [33], the 7
160
remaining studies were assessed using an evaluation derived from the three aforementioned
161
scales. The aim of this analysis was to evaluate study quality and identify areas of
162
methodological weakness. The scale utilises 10-item criteria ranging from 0-20 points with the
163
score for each criterion reported as follows: 0 = clearly no; 1 = maybe; and 2 = clearly yes.
164
Based on this procedure, the studies were classified as follows: low methodological quality (≤
165
50% of total points); good methodological quality (51–75% of total points); and excellent
166
methodological quality (> 75% of total points) [33]. All of the criteria included are reported in
167
Table 1.
168
169
***Please, add here Table 1***
170
171