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The strength-endurance continuum revisited: a critical commentary of the recommendation of different loading ranges for different muscular adaptations

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Abstract

Objectives: The accepted wisdom within resistance training is that differing loads and corresponding repetition maximum (RM) ranges are optimal for inducing specific adaptations. For example, prominent organizations and their respective publications have typically prescribed heavy loads for maximal strength increases (>85% 1RM/<6RM), more moderate loads for hypertrophy (67-85% 1RM/6-12RM) and lighter loads for local muscular endurance (LME; <67% 1RM/>12RM). Since we believe these recommendations originate from a misunderstanding and misinterpretation of DeLorme's strength-endurance continuum, the aim of this narrative review is to discuss the preponderance of research surrounding training load and strength and LME adaptations. Design & Methods: Narrative Review Results: The current body of literature fails to support recommendations for the use of specific loads for specific strength, hypertrophy or LME adaptations. Furthermore, that the strength-endurance continuum originally presented by DeLorme was never intended to compare the use of heavier- and lighter-load resistance training, but rather to consider the adaptations to strength training and aerobically based endurance exercise. Finally, a lack of clarity considering absolute- and relative- LME has confounded understanding of this adaptation. Conclusions: The body of research supports that absolute LME appears to adapt as a result of maximal strength increases. However, relative LME shows minimal response to strength training with either heavier- or lighter-loads. We present the limitations of the current body of research and promote specifically detailed recent research as well as the importance of generality of strength and LME in both sporting and real-world settings.
Review
The strength-endurance continuum revisited:
a critical commentary of the recommendation of
different loading ranges for different muscular adaptations.
James P. Fisher, James Steele, Patroklos Androulakis-Korakakis, Dave Smith, Paulo Gentil, Jürgen Giessing
Objectives: The accepted wisdom within resistance training is that differing loads and corresponding repetition maximum (RM)
ranges are optimal for inducing specific adaptations. For example, prominent organizations and their respective publications
have typically prescribed heavy loads for maximal strength increases ( ≥ 85% 1RM/ ≤ 6RM), more moderate loads for
hypertrophy (67-85% 1RM/6-12RM) and lighter loads for local muscular endurance (LME; ≤ 67% 1RM/ ≥ 12RM). Since we
believe these recommendations originate from a misunderstanding and misinterpretation of DeLorme’s strength-endurance
continuum, the aim of this narrative review is to discuss the preponderance of research surrounding training load and
strength and LME adaptations.
Design & Methods: Narrative Review
Results: The current body of literature fails to support recommendations for the use of specific loads for specific strength,
hypertrophy or LME adaptations. Furthermore, that the strength-endurance continuum originally presented by DeLorme was
never intended to compare the use of heavier- and lighter-load resistance training, but rather to consider the adaptations to
strength training and aerobically based endurance exercise. Finally, a lack of clarity considering absolute- and relative- LME
has confounded understanding of this adaptation.
Conclusions: The body of research supports that absolute LME appears to adapt as a result of maximal strength increases.
However, relative LME shows minimal response to strength training with either heavier- or lighter-loads. We present the lim-
itations of the current body of research and promote specif ically detailed recent research as well as the importance of gener-
ality of strength and LME in both sporting and real-world settings.
(Journal of Trainology 2020;9:1-8)
Key words: strength local muscular endurance load intensity repetitions, resistance training
INTRODUCTION
Traditionally, resistance training has been prescribed based
upon knowledge of the maximal load a person can lift for a
single repetition (i.e., 1-repetition maximum; 1RM) and then
training performed using a predetermined percentage of this
load based on the desired outcome (e.g. increased strength,
hypertrophy, or local muscular endurance; LME). The promi-
nent organisations within strength training (the National
Strength and Conditioning Association [NSCA] and
American College of Sports Medicine [ACSM], have typically
prescribed training loads as follows: ~ 60-70% 1RM for nov-
ice or intermediate trainees, or ~80-100% 1RM for advanced
individuals for strength; ~70-85% 1RM for novice or interme-
diate, or ~70-100% 1RM for advanced individuals for hyper-
trophy; and ≤ 67% 1RM for local muscular endurance
(LME;1,2). This is often referred to as the repetition maximum
continuum or the strength-endurance continuum; the idea that
heavier loads optimise strength adaptations and lighter loads
optimise LME adaptations. We propose that this is the gener-
ally accepted wisdom amongst personal trainers and strength
and conditioning coaches based on these long-standing
beliefs.
However, cu rrent literature3,4 supports the view that heavy-
and light-loads produce equivalent increases in strength
(when measured by impartial methods to parse-out improve-
ments in skill due to familiarity of the testing mode) when
exercise is continued to momentary failure. For instance,
improving maximal strength (as measured by 1RM in a spe-
cific exercise) might best be achieved by practicing heavy/
maximal repetitions of that specific exercise (e.g., to improve
a bench press 1RM a person might be best advised to practice
a bench press 1RM3-6). Certainly, evidence has supported the
notion that motor schemata are both highly movement specif-
ic as well as load/force specif ic7. As such, this appears domi-
nantly a product of rehearsing the synchronous motor unit
recruitment required for maximal lifts (e.g., bench press), as
well as their coordinated recruitment patterning for the tech-
nical elements of more complex exercises (e.g., clean and
jerk). However, evidence suggests that the apparent superiori-
ty of heavy/maximal loading might be absent when using
impartial testing methods. For example, Mitchell et al.8
reported greater increases in 1RM for groups training with
1
Received December 16, 2019; accepted January 18, 2020
From the Solent University, East Park Terrace, Southampton, UK (J.P.F., J.S., P.A.K.), Manchester Metropolitan University, Crewe, UK (D.S.),
Faculdade de Educação Física e Dança, Universidade Federal de Goiás, Goiânia, Brazil (P.G.), and University of Koblenz-Landau, Germany (J.G.)
Communicated by Takashi Abe, PhD
Correspondence to: Dr. James P. Fisher, Solent University, East Park Terrace, Southampton, UK.
Email: James.Fisher@solent.ac.uk
Journal of Trainology 2020;9:1-8 ©2012 The Active Aging Research Center http://trainology.org/
Journal of Trainology 2020;9:1-82
80% of 1RM compared to those training with 30% 1RM.
However, when tested using isometric torque (an impartial
testing method since neither group had trained using isomet-
ric contractions) there were no between group differences in
strength increases. Fisher, Ironside and Steele9 reported simi-
lar f indings; that dynamic knee extension exercise at either
80% or 50% of maximum torque produced similar increases
in maximal isometric strength. This is further supported by a
recent systematic review and meta-analysis considering high-
( > 60% 1RM) and low- ( ≤ 60% 1RM) load training.4 The
authors reported statistically significant differences in favour
of heavy loads when considering 1RM, yet no signif icant dif-
ference when considering impartial (isometric) strength test-
ing.
Furthermore, evidence suggests that hypertrophic adapta-
tions can be equally attained almost irrespective of training
load used.4,8 For example, the aforementioned study by
Mitchell et al.8 repor ted similar increases in quadriceps mus-
cle volume between groups training at 30% and 80% 1RM. In
addition, a comprehensive review comparing loads > 60%
1RM to those ≤ 60% 1RM concluded “muscle hypertrophy
can be equally achieved across a spectrum of loading rang-
es4. The caveat to these similar increases in muscle size irre-
spective of load appears to be intensity of effort, that is; that
similar adaptations are attained so long as participants train
to momentar y failure.
In view of these publications it is interesting that there have
been no recent reviews of the strength-endurance continuum
in consideration of the relationship between maximal strength
(e.g., 1RM) and LME adaptations. As such, we believe the
area warrants a narrative discussion of the origins of this con-
tinuum as well as to discuss often cited articles supposedly
supporting a continuum and perhaps attempt to explain why
differing adaptations might occur. With this in mind, the aim
of this commentary is to discuss the limitations of the notion
of the repetition maximum /strength-endurance continuum
and provide more evidence-based recommendations for prac-
titioners.
Absolute- and Relative- Muscular Endurance
A notable problem with any recommendations pertaining to
strength and LME adaptation is the failure to differentiate
between absolute and relative LME. Absolute LME should be
considered the number of repetitions possible at a given abso-
lute load, whereas relative LME is the number of repetitions
possible at a given %1RM.10 In testing, these would be repre-
sented by use of either an absolute load (that does not change
in relation to strength or following any strength training inter-
vention), or, in contrast, a relative load (that is always mea-
sured as a percentage of maximal strength. e.g. %1RM). The
ACSM 2 (page 697) stated:
“RT has been shown to increase absolute LME (i.e., the
maximal number of repetitions performed with a specific
pre-training load), but limited effects are observed in rel-
ative LME (i.e., endurance assessed at a specific relative
intensity or %1RM)…
…A relationship exists between increases in strength and
LME such that strength training alone may improve
endurance to a certain extent.”
This statement appears to conflict with the guidance based
on loading and repetition ranges.1,2 As such we should ques-
tion why, if absolute LME improves with maximal strength
and relative LME shows limited effects, would we recom-
mend that individuals use different training loads or repeti-
tion ranges to target strength or LME.
Clarity regarding the work of DeLorme
The above guidelines by the ACSM2 and NSCA1 cite the
work of Anderson and Kearney11, Stone and Coulter10, and
Campos et al.12; each of which will be discussed later herein,
in support of what has become the accepted “wisdom” in
strength and conditioning; the strength-endurance continuum.
Each of these studies cites, in turn, the seminal work of
DeLorme13 where he discusses the use of heavy resistance
exercise rather than endurance exercise for restoration of
muscular strength and power in injured veterans. However,
each of these studies, and many others, appear to have misin-
terpreted, and as such misrepresented, DeLorme’s hypothesis
and f indings. For example, DeLorme clarifies “By ‘power-
building’ exercises we mean exercises in which a heavy resis-
tance is used for a low number of repetitions. ‘Endurance-
building’ exercises are those in which a low-resistance is used
for a large number of repetitions” (page 650).
Whilst DeLorme states endurance exercise to be low-resis-
tance/high-repetition, he further clarifies examples as stair-
climbing, walking, bicycling and similar low-resistance exer-
cises (651). He continues: How illogical it would be for a
track man to train for long-distance running events solely by
doing knee bends with heavy weights on his shoulder, or a pro-
fessional weight-lifter to train for heavy lifts solely by running
several miles a day” (page 651). In fact, within his 1945 arti-
cle he provides guidance that “the workout must begin with a
weight considerably less than the 10RM, so that when the
10RM has been reached, seventy to 100 repetitions have been
performed (page 648). Notably this number of repetitions
was completed across 7-10 sets of 10 repetitions. Furthermore,
DeLorme does not use the term muscular endurance through-
out this article, in contrast to what other authors have stat-
ed10-12. Instead, DeLorme was making reference to what is
now considered aerobically based endurance exercise modali-
ties (e.g., “stairclimbing, walking, bicyclingand “running
several miles a day”). In this discussion of the work of
DeLorme it is important to clarify that he developed these
ideas in later publications, and in 1948 DeLorme and
Wat k i n s14 clarified that “it has become apparent that the term
‘heavy resistance exercises’ bears false implications, and the
term ‘progressive resistance exercises’ was suggested as being
far more appropriate” (page 263). It is, thus, evident that
DeLorme did not intend to differentiate between heavy- and
light-load resistance training per se, but rather to determine
the disparity in adaptations between progressive resistance
exercise and aerobically based endurance exercise. It is per-
Fisher et al. The strength-endurance continuum revisited 3
haps also noteworthy that in this article DeLorme and
Wat k i n s14 suggested a decreased training volume, from 7-10
sets to, the now commonly accepted, 3 sets of 10 repetitions.
Perhaps notably though, this was described in the following
format;
First set of 10 repetitions - use ½ of 10 repetition maximum
Second set of 10 repetitions - use ¾ of 10 repetition maxi-
mum
Third set of 10 repetitions - use 10 repetition maximum
In this case DeLorme appears to be suggesting 2 submaxi-
mal sets and then a single set to repetition maximum, with the
technical advice that:
The movements are done smoothly, rhythmically, and
without haste, but not so slowly that the mere holding of
the weight will tire the patient. Quick or sudden motions
while exercising are to be avoided.” (page 646).
It is unclear as to whether DeLorme was suggesting to train
to momentary failure, or to a repetition maximum, as have
been recently more clearly defined.15 Nevertheless, it is clear
that the final set in this protocol was intended to require at
least a near maximal effort. It is perhaps also worth mention-
ing that DeLorme13 (page 649) describes the principles of
double-progression; that, when performing a given exercise,
as the number of repetitions increases beyond a target range
(e.g., 8-12) a person should increase the load being used,
which has the subsequent effect of reducing the repetitions
possible, and so the trainee repeats the process as he or she
becomes stronger. Whilst DeLorme does not provide a cita-
tion for this concept our research suggests that this originates
from Allan Calvert in his text “The First Course in
BodyBuilding and Muscle Developing Exercises”.16 As an
example of double progression; a person who could initially
only perform 8 repetitions with a load of 100kg progresses
over time to be able to perform 12 repetitions with 100kg
(with all other exercise factors being equal; repetition dura-
tion, range of motion, exercise technique, etc.). He or she then
increases the load to 105kg and the number of repetitions
which can be performed decreases to 8 repetitions. If we
accept that an 8RM is a measure of strength, then the necessi-
ty of this principle to increase strength is something of a para-
dox; it is built on a premise that as we increase the number of
repetitions we perform we increase strength sufficiently to
increase the training load. But that increasing the load is
important to continue increasing strength. Ultimately, this
principle is anecdotally used to support the strength-endur-
ance continuum and that of specificity: lifting heavier weights
increases maximal strength, whilst performing a greater num-
ber of repetitions with a lighter weight increases local muscu-
lar endurance. However, it seems far more likely that double
progression in this sense represents a more time-efficient, but
not essential, method of training. For example, if performed at
a repetition duration of 2s concentric: 2s eccentric, perform-
ing 8-12 repetitions represents a time of 32-48 seconds. If a
person were to continue increasing strength with an absolute
load, and thus continue increasing the number of repetitions
they could perform, then this time under load might become
impractical, and other sensations such as discomfort might
become a factor for exercise cessation (see later section on
effort and discomfort).
Repetition Maximum Continuum
Within the fourth edition of “Essentials of Strength Training
and Conditioning”, Haff and Triplett1 provide a table (17.9,
page 458) clarifying loads/repetition ranges for optimizing
specific strength (≥ 85% 1RM/ ≤ 6RM), hypertrophy (67-85%
1RM/6-12RM), and muscular endurance (≤ 67% 1RM/
12RM) adaptations. However, the references cited do not
wholly support these recommendations. For example, two of
the eight citations are textbooks17,18, and a third citation is a
chapter from a book.19 The fourth and fifth citations are a
commentary/review article20, and an ar ticle aimed at provid-
ing strength training recommendations by Kraemer and
Koziris21. None of these citations are empirical studies pre-
senting data. Of the remaining three citations, the first empir-
ical study, that of Berger22, considered bench press strength
increases for 199 male college students following a 12-week
intervention. Berger22 reported more favorable strength
increases for 8RM training compared to both higher- (10RM
and 12RM) and lower- (2RM) repetition maximum training.
The second empirical study, that of Herrick and Stone23, com-
pared previously untrained females divided into one of two
groups; either progressive resistance exercise (PRE; 3 sets of
6RM for 15 weeks) or periodized resistance exercise (PER; 8
weeks of 3 sets using 10RM, 2 weeks of 3 sets using 4RM and
2 weeks of 3 sets using 2RM, with 1 week of active rest
between each cycle). The authors measured bench press and
back squat pre- and post-inter vention as well as every 3
weeks (totaling 6 testing time points) finding significant with-
in-group strength increases for both groups with no between-
groups differences. The third empirical study, by Tesch and
Larsson24, took biopsies from the vastus lateralis and medial
deltoid muscles from 3 competitive bodybuilders, as well as
measuring strength of the quadriceps using isokinetic dyna-
mometry. They compared this data to reference groups of
physical education students and national elite power- and
weight-lifters. They did not conduct an intervention that com-
pared training adaptations following the proposed differing
repetition ranges. Interestingly, the authors reported similar
muscle morphology between the bodybuilders and the physi-
cal education students (% fast twitch muscle fibres, % fast
twitch muscle area, fast twitch: slow twitch ratio, as well as
fast twitch-, slow twitch- and mean- fibre area), stating:
We did not observe any sign of individual muscle fiber
enlargement in either thigh or shoulder muscles of suc-
cessful bodybuilders. Thus, despite the considerably
greater body weight per height and less body fat in body-
builders compared to habitually trained and age matched
men, mean fiber area did not differ.” (page 305).
It can only be assumed that this study was cited based on
the comments in the discussion that bodybuilders typically
perform 3 or more sets of 6-12 repetitions to concentric fail-
Journal of Trainology 2020;9:1-84
ure, interspersed with short recovery periods - which is
aligned to the NSCA recommendation cited above.1 However,
based on this as well as the previous citations it is not clear
how Haff and Triplett1, nor the organization (NSCA), are able
to justifiably endorse such recommendations.
Support for a Repetition-Maximum Continuum
Since we have clarified that the strength-endurance continu-
um was never proposed to present disparate training adapta-
tions to heavier- and lighter-loads in resistance training, we
shall use the term repetition-maximum continuum in fur ther
discussion of this concept. The three often cited empirical
studies used (by the ACSM/NSCA) to support the repetition
maximum continuum shall now be considered chronological-
ly.
Anderson and Kearney11
The publication by Anderson and Kearney11 is a common
citation in favor of the repetition maximum continuum and as
such, it is worth discussing in detail the research design.
Forty-three untrained males were divided into heavy-load
(HL, n = 15; 3sets of 6-8RM), moderate load (ML, n = 16; 2
sets of 30-40RM), and light-load (LL, n = 12; 1 set of 100-
150RM) training groups. Participants trained using the bench
press exercise 3 x / week for 9 weeks. The authors reported
pre- and post-intervention 1RM, repetitions for absolute-LME
using 27.23kg, and repetitions for relative-LME using 40% of
pre- and post-intervention 1RM. Analysis of variance
revealed significant increases in 1RM for all groups
(HL = 13.7kg, ML = 5.4kg, and LL = 3.2kg) with a significant
group x time interaction. The authors found significant pre- to
post-intervention increases for absolute-LME (p < 0.0001;
HL = 9.5, ML = 14.4, and LL = 14.6 repetitions), but between-
group differences were not statistically significant (p < 0.13).
For relative-LME the authors reported significant pre- to
post-intervention changes (p < 0.0001) as well as group x test
interaction (p < 0.0001). Follow up analyses revealed signifi-
cant increases in the number of repetitions for ML and LL
groups which were also statistically significantly greater than
the change in repetitions for the HL group. There were no sig-
nificant differences for the change in the repetitions between
the ML and LL groups. The values for change in repetitions
from pre- to post-intervention for relative-LME were HL =
-2.86 repetitions/-6.99%, ML = 8.81 repetitions/+22.45%, and
LL = 10.67 repetitions/+28.45%. The authors reported a
tempo of 40 repetitions per minute, for muscular endurance
testing as well as training for the ML and LL groups.
It is interesting that whilst the HL group increased their
1RM by 13.7 kg (compared to only 5.4 kg and 3.2 kg for ML
and LL groups, respectively), the number of repetitions they
were able to perform at the absolute load of 27.23 kg (equiva-
lent to 40% of their pre-intervention 1RM, and only 33% of
their post-intervention 1RM) increased to a lesser degree
(although not significantly so) than the ML and LL groups
(14.4 and 14.6 repetitions, respectively). Furthermore, that
when performing repetitions assessed for relative-LME at
40% 1RM, the ML and LL groups achieved increases in the
number of repetitions with an increased load (8.8 and 10.7
repetitions, respectively). In considering the data in more
detail and by group, the LL group increased their 1RM by 3.2
kg, which resulted in an increase to their load at relative-LME
(40%) of only 1.3 kg, whilst the ML group increased their
1RM by 5.4 kg, which resulted in an increase to their load at
relative-LME (40%) of only 2 kg. It seems reasonable to sug-
gest that the increased number of repetitions for relative-LME
for the ML and LL groups might be a result of such small
changes in the loads used (i.e. < 2 kg). In this sense, the rela-
tive-LME test might have been closer to an absolute-LME
test.
It is interesting that, in the introduction, Anderson and
Kearney11 rationalize their own research by citing three stud-
ies25-27 which they claim challenge the observations of
DeLorme13. However, these studies, as well as their own,
compare heavy-load, low-repetition vs. light load, high-repeti-
tion resistance training. As clarified, this study design does
not resemble, and thus does not challenge, DeLorme’s obser-
vations regarding progressive resistance exercise compared
with aerobically based endurance modalities. Furthermore,
each of these three studies supported that both heavy- and
light-loads produce similar enhancement of muscular strength
and LME. Indeed, Anderson and Kearney11 stated that the
findings of Delateur et al.26 revealed that “choice of weights is
not of prime importance as long as the repetitions are contin-
ued to the point of fatigue” (page 248). They continue
Strength and endurance thus appear to be two closely related
attributes of the well-trained muscle” (page 248).
Stone and Coulter10
A further study considering heavy-, moderate- and lighter-
loads in relation to increases in 1RM, absolute-LME and rela-
tive-LME is that of Stone and Coulter10. The authors divided
fifty untrained females into heavy-load (HL, n = 17; 3sets of
6-8RM), moderate load (ML, n = 16; 2 sets of 15-20RM), and
light-load (LL, n = 17; 1 set of 30-40RM) training groups.
Testing was performed for bench press (BP) and back squat
(BS) exercises with maximal strength measured using 1RM,
absolute-LME measured as repetitions at 15.9kg (BP) and
25kg (BS), and relative-LME measured using repetitions at
45%1RM (BP) and 55% 1RM (BS). The authors stated that
relative-LME was tested at two loads; load 1 involved pre-
and post-testing repetitions at a given percentage of the pre-
intervention 1RM. However, re-testing muscular endurance
post intervention using the same pre-intervention %1RM is
absolute- not relative-LME. Thus, the authors performed two
absolute-LME tests; for bench press they used 15.9kg and
45% of pre-intervention 1RM, and for back squat they used
25kg and 55% of pre-intervention 1RM. The second relative-
LME test using load 2 was a true relative-LME test where the
pre-test used a % of the pre-intervention 1RM, and the post-
test used the same percentage of the post-intervention 1RM.
Tempo was described as 40 and 30 repetitions per minute for
the bench press and back squat, respectively. The authors
reported no significant differences between the three proto-
cols for improvements in 1RM, or absolute-LME, and report-
ed no significant increases in relative-LME. It is, therefore,
surprising that the NSCA1/ACS M 2 cited this paper for the use
Fisher et al. The strength-endurance continuum revisited 5
of higher repetition ranges for improving muscular endurance
when the results do not support this claim.
Campos et al.12
Perhaps the most notable research cited to support a repeti-
tion-maximum continuum is that of Campos et al.12. Thirty-
two physically active but previously untrained young males
were divided into low repetition (Low Rep; 3-5RM, n = 9),
intermediate repetition (Int Rep; 9-11RM, n = 11), high repeti-
tion (High Rep; 20-28RM, n = 7), and non-exercising control
(CON; n = 5) groups. The exercising groups performed leg
press, squat and knee extension exercises 2x/week for the f irst
4 weeks and 3x/week for the last 4 weeks. Par ticipants were
tested pre- and post-intervention for 1RM and, after a 4-5
minute recovery, they completed as many repetitions as possi-
ble with 60% 1RM (the authors do not clarify whether this
was relative- or absolute- LME in the article, but this descrip-
tion and personal correspondence have confirmed this to be a
test of relative LME). The Low Rep group showed signifi-
cantly greater 1RM increases in leg press and squat exercises
compared to the other groups, but the increase in k nee exten-
sion 1RM was signif icantly greater than the High Rep group
only. The authors reported that the three training groups sig-
nificantly improved in the number of repetitions performed
with 60% 1RM in the squat exercise, but neither the Int Rep
group nor the Low Rep group showed a significant improve-
ment in the leg press or knee extension exercises. In fact, the
number of repetitions significantly decreased in the Low Rep
group for the leg press. The authors did not report a tempo or
repetition duration for testing or training.
The authors provide data in the form of figures, rather than
specific numerical values, and as such these cannot be dis-
cussed in detail. Indeed, in private correspondence we have
been advised that the raw data is no longer available for con-
sideration/analyses. However, in an attempt to better consider
this study, we have used a digitization program to calculate
the values from Figure 3 in the article12 (WebPlotDigitizer,
v3.12; Ankit Rohgati; http://arohatgi.info/WebPlotDigitizer/
index.html). We estimate pre-intervention 1RM values for the
leg press to be ~310kg for Low Rep, ~294kg for Int Rep, and
~300kg for High Rep (reported as not significantly different
between groups). The post-intervention 1RM values are esti-
mated as ~498kg for Low Rep (reported as 61% improve-
ment), ~398kg for Int Rep (reported as 36% improvement) and
~364kg for High Rep (reported as 32% improvement,
although using the values extracted using the digitization
software we calculate a 21% improvement). With a similar
method using the authors’ Figure 4, the local muscular endur-
ance testing appears to have produced estimated pre-interven-
tion values for the leg press of ~40 repetitions for Low Rep,
~39 repetition for Int Rep, and ~35 repetitions for High Rep.
The corresponding estimated post-testing repetitions were
~32 repetitions for Low Rep (reported as -20% change), ~43
repetitions for Int Rep (reported as 10% improvement), and 68
repetitions for High Rep (reported as 94% improvement).
It is, therefore, sur prising that the low rep group, increasing
their 1R M strength by ~188kg/61% decreased their relative
muscular endurance from 40 repetitions with ~186kg to 32
repetitions with ~298kg. In contrast, and more surprisingly,
the high rep group increased their 1RM strength by
~64kg/21% but also increased their relative muscular endur-
ance from 35 repetitions with ~180kg to 68 repetitions with
~218kg. Aside from the possibility that low rep training truly
does produce greater maximal strength increases but dimin-
ish relative muscular endurance performance whilst high rep
training produces (albeit lesser) strength increases and far
superior relative muscular endurance improvements (com-
pared to low rep training), we have hypothesized other factors
which might have confounded these results. For example (and
while we believe this to be highly improbable), though partici-
pants were randomized the relatively small sample size per
group may have resulted in heterogeneous groupings regard-
ing genetic predisposition to either maximal strength increas-
es or muscular endurance increases for low- and high-rep
groups respectively. Indeed, the wide heterogeneity in
response variation to resistance training is well known28 and,
though it is difficult to differentiate true intervention
response variation from other random variation29, it is well
evidenced that some individuals can show considerable
improvements in some outcomes but not others and vice
versa30,31. Another factor, might be that the strength increase
for the low rep group could be partially a result of improved
motor schema in the practice of synchronous recruitment3,
and the skill of the exercise itself par ticularly as the testing
resembled the training (although we might expect lower skill
increases in a leg press exercise, whether plate loaded or
selectorized compared to a more complex movement such as a
squat). Finally, and as discussed later, we might consider that
the high rep group became acclimatized to the discomfort of
performing a greater number of repetitions than the low rep
group (20-28RM compared to 3-5RM, respectively) through-
out the 8-week training intervention.
Interestingly despite each of these studies being used to
support a repetition maximum continuum of ≤ 6RM for
strength, 6-12RM for hypertrophy, and ≥ 12RM for LME
adaptations (NSCA1, page 458), only the study by Campos et
al.12 study tested these repetition ranges (e.g. strength [low
rep] 3-5RM, hypertrophy [int rep] 9-11RM, and LME [high
rep] 20-28RM). Furthermore, only Campos et al.12 took any
measurement of muscle hypertrophy. The authors reported
that a hypertrophic effect was observed in type I, IIA and IIB
muscle fibre types in the low- and inter mediate-RM training
groups only. There were no significant differences between
the low- and intermediate- RM groups for muscle fibre hyper-
trophy (low RM = 12.4, 22.9, 25.3% and inter mediate
RM = 13.1, 16.3, 27.2%, for type I, IIA, and IIB fibre types,
respectively).
Effort and Discomfort
When we consider heavier- and lighter-load RT, a factor
that might become important when trying to exercise to
momentary failure is that of discomfort compared to effort.
There is a growing body of research supporting that discom-
fort (defined as the physiological and unpleasant sensations
associated with exercise32,33) is greater when performing exer-
Journal of Trainology 2020;9:1-86
cise to momentary failure using a lighter- (50% MVC) com-
pared to a heavier- (80% MVC) load in both males and
females9,34. This is potentially a result of increased blood lac-
tate and cortisol accumulation35 and primarily thought to
result from afferent feedback mechanisms33. As such, it seems
likely that the ability to reach momentary failure with lighter
loads could be impaired by the discomfort during resistance
exercise36. This, in turn, might negatively impact the chronic
muscular adaptations across the duration of an intervention
when compared to a heavier-load group, who can reach
momentary failure and attain the desired effort with far less
discomfort. An example might be the Anderson and
Kearney11 study where participants in the HL group per-
formed 3 sets of 6-8 repetitions to momentary failure, where-
as the ML and LL group performed 30-40 and 100-150 repeti-
tions respectively. At the rate of 40 repetitions per minute this
equates to ≤ 12 seconds per set for the HL group (performing
3 sets = 36 seconds under load), 60 seconds per set for the ML
group (performing 2 sets = 2 minutes under load) and 3 min-
utes 40 seconds per set for the LL group.
Furthermore, the changes to LME testing for lighter-load/
higher repetition groups might be a potential adaptation to
discomfort as a result of the training intervention, i.e., per-
forming very high-repetition sets; e.g. 20-28RM12, 30-4010,11
and 100-150RM11. A test of LME will likely stimulate consid-
erable discomfort as a person nears maximal effort and task
failure and as such training at lighter loads/higher repetitions
might not incur neuromuscular or morphological adaptations
that improve LME but rather accommodate familiarisation
and increased tolerance of the discomfort associated with a
test of LME. Certainly, recent work has shown that repeated
exposure to exercise conditions known to cause discomfort,
such as high intensity interval training, increases pain toler-
ance and this might partly explain improvements in time to
task failure37. Indeed, there might be mechanisms beyond
muscular adaptations by which the repetition maximum con-
tinuum applies. For example, by training at heavier/maximal
loads a person might improve strength more than at lighter
loads as a result of enhanced skill, along with practicing high
synchronous motor unit recruitment, and by training at lighter
loads a person might improve LME as a result of the familiar-
isation and tolerance to the discomfort of lighter-load exer-
cise.
Hypertrophic adaptations
Whilst this narrative review has primarily been focused
upon the concurrent adaptations in maximal strength and
absolute muscular endurance across a range of training loads,
hypertrophy has often been considered in context of the few
respective studies which have tested the “hypertrophy-zone”
of the repetition maximum continuum (e.g. 67-85% 1RM/6-
12RM1). With a dearth of research, both the NSCA1 and
ACSM 2 have failed to provided support for the claims that
this loading range is optimal for muscular growth. As dis-
cussed earlier, the repetition maximum continuum, displayed
as table 17.9 (page 458) in “Essentials of Strength Training and
Conditioning1 cites only 3 empirical studies. Those of
Berger22 and Herrick and Stone23 did not take any measure-
ment of muscle size. The final study, that of Tesch and
Larsson24, was observational in comparing intramuscular
properties following biopsy between elite bodybuilders and
reference groups of physical education students. The authors
did not perform pre- or post-intervention measurements and
did not consider different loads/repetition ranges to scientifi-
cally test the repetition maximum continuum. More so, whilst
the authors suggest that bodybuilders typically train using 3
sets of 6-12 repetitions, the data presented does not support
that this is optimal for muscle growth. In fact, as stated above,
the authors report similar muscle morphology when compar-
ing the elite bodybuilders to the physical education reference
group.
Of the other often cited studies, neither Anderson and
Kearney11, nor Stone and Coulter10 took measurements of
muscle size. Campos et al.12 considered hypertrophic adapta-
tions measured by muscle biopsy in assessment of the repeti-
tion maximum continuum, reporting similar increases in type
I, IIA and IIB muscle fibres between the groups which
trained using low reps (3-5RM) and intermediate reps
(9 -11R M).
More recent publications provide conf licting evidence to a
repetition maximum continuum. Mitchell et al.8 reported sim-
ilar increases in quadriceps muscle volume between groups
training using 30% and 80% 1RM, and a meta-analysis and
systematic review supported that hypertrophic adaptations
are similar between loads > 60% 1RM and loads < 60%
1RM4.
CONCLUSIONS
The aim of this piece was to review and challenge the com-
monly accepted wisdom of the repetition-maximum continu-
um as well as to clarify the work of Thomas DeLorme and the
strength-endurance continuum. The data and discussions pre-
sented suggest that the guidance of specific loads/repetition
ranges for strength, hypertrophy, or LME are not supported
by the evidence. When reviewing the data it appears that
strength increases are not only attainable, but effectively the
same, at both very heavy (maximal/near maximal) loads and
more moderate loads of 8-12RM. Furthermore, that as
strength increases so too does absolute-LME. Finally, that
hypertrophic adaptations appear similar across a spectrum of
loading ranges where exercise is performed to momentar y
failure.
Whilst many persons train for maximal strength, and as
such might practice heavy/maximal resistance training under
the guidance of practicing the test”, we should not underval-
ue the importance of adaptations in absolute LME in both
sports and real-world activities. The reality is that a person
seldom performs single maximal efforts, but rather repeated
muscle actions. A prime example in a sporting environment
might be the 225lb bench press for as many repetitions as pos-
sible in the NFL Combine test. Prospective athletes are not
asked to perform a 1RM test but rather a test of absolute LME
(e.g. the load is set at 225lbs irrespective of player position or
weight). A lay example might be the movement of our own
Fisher et al. The strength-endurance continuum revisited 7
bodyweight, which, whilst it might f luctuate to a degree, is
generally relatively constant; as such tests of press-ups, pull-
ups, or dips, as well as more functional tasks such as rising
from a chair, climbing a flight of stairs, etc. are effectively
tests of absolute LME.
Practical Applications
With the above in mind, and since training specifically for
strength, hypertrophy or LME is often performed as part of a
periodised resistance training programme we caution strength
and conditioning coaches, personal trainers and trainees in
the use of specific loads/repetition ranges for specific out-
comes (e.g. strength, hypertrophy, LME). It is our view that
the preponderance of research does not support a repetition-
maximum continuum, but rather we suggest that resistance
training be performed to a high degree of effort and that loads
are self-selected based on convenience, safety, and psycho-
physiological factors such as discomfort, etc. The data sug-
gests that following this guidance similar strength adaptations
will occur irrespective of load, and that absolute LME
increases with maximal strength, whereas relative LME
shows little response to strength increases. Persons training
specifically for muscle hypertrophy are able to self-select a
load based on personal preference, accessibility, etc.
Compliance with ethical standards
Funding
No sources of funding were used to assist in the preparation
of this article.
Conflicts of Interest
James Fisher, James Steele, Patroklos Androulakis-
Korakakis, Dave Smith, Jürgen Giessing, and Paulo Gentil
declare that they have no conflicts of interest relevant to the
content of this article.
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... Studies that have used a low (2-6 repetitions) compared to a moderate (8)(9)(10)(11)(12) repetitions) number of repetitions per set have found similar increases in LME [7,8]. Therefore, the effectiveness of a higher number of repetitions for the development of LME may be observable when the difference in repetitions per set between interventions is large (e.g. ...
... However, limited effects are observed during a LME test using %1RM POST . Fisher and colleagues [10] examined data related to this topic and concluded that with increases in muscle strength there appears to be little change in LME when assessed via %1RM POST . An explanation for this conclusion is based on the maximal number of repetitions possible at a relative percentage of 1RM being relatively stable with mild variations within an individual [11]. ...
... Where possible, subgroup analyses were conducted to explore changes in LME following specific repetition ranges: low (≤ 6 repetitions), moderate (7-14 repetitions) and high (≥ 15 repetitions). These repetition ranges were selected since they closely match the ACSM recommendations for targeting muscle strength (1-6 RM), hypertrophy (6)(7)(8)(9)(10)(11)(12), and endurance (> 15 repetitions) [2]. Further, there was examination of individual effects of training (e.g. ...
Article
Objectives To examine the effect of total repetitions per set on local muscular endurance (LME) assessed via maximal repetitions to concentric muscular failure using loads based on a percentage of pre-intervention one-repetition maximum (%1RMPRE) and post-intervention 1RM (%1RMPOST). News Four electronic databases were searched using terms related to LME and resistance training. Studies were deemed eligible for inclusion if they met a strict criteria. Random effects (Hedges’ g) meta-analyses were undertaken to estimate the effect of lower versus higher repetitions on LME assessed via two methods. Possible predictors that may have influenced training-related effects were explored using univariate analyses. Fourteen studies were included in this review. There was a large effect in favour of a higher number of repetitions per set for LME assessed by %1RMPOST (g = 0.97, P < 0.001, 95% CI 0.53 to 1.40), but no difference when assessed by %1RMPRE (g = 0.09, P = 0.49, 95% CI −0.17 to 0.35). A sub-analysis revealed a large effect in favour of high repetitions (median range of 18–125) compared to moderate repetitions (median range of 7–13) for LME assessed by %1RMPOST (g = 1.08, P < 0.001, 95% CI = 0.60 to 1.56). “Changes in strength” moderated the lower versus higher repetition effects on LME assessed by %1RMPOST (P = 0.002). Conclusion Resistance training with a higher number of repetitions (≥ 15) is more effective than lower repetitions for enhancing LME when assessed using a given percentage of post-intervention 1RM but not pre-intervention 1RM.
... [15][16][17] More recently, 2 reviews have confronted the accepted wisdom in strength training-that of the repetition-maximum or strength-endurance continuum-suggesting instead that adaptations are not load specific, but rather a range of loads can produce similar adaptations where exercise is performed to momentary failure. 18,19 With this in mind, we know training to momentary failure is sufficient to induce increases in muscle size and strength, but we are still unclear as to whether it is necessary. ...
... This guidance allows the freedom to prescribe exercise based on a more time-efficient, effort-based paradigm as opposed to on load/volume/repetitions, as has typically been suggested. This aligns with the work of Fisher et al. 18 and Schoenfeld et al. 19 , who have shown that, when training is performed to momentary failure, a range of loads and repetitions can be used to achieve a number of desirable adaptations, including muscular strength, local muscular endurance, and muscle hypertrophy, and more importantly, an array of health benefits. Fig.1 Examples of possible candidate models of dose-response. ...
... Furthermore, whilst evidence has supported that, when training to failure, strength and muscle mass adaptations are similar across a range of loads (e.g. 30% -90% 1-repetition maximum; RM) [19,50], virtual personal training often relies on trainees utilising bodyweight exercise or what weights and equipment they may have available at home. During lockdown, despite most people performing resistance training at home, most utilised higher repetition ranges suggesting the use of lighter loads [53]. ...
... In this sense, we can assume that virtual personal training, at the least by this facility, is an efficacious approach to permit continued engagement in high intensity of effort resistance training. This might be of importance for the maintenance and improvement of physiological adaptations since effort seems a key driver for hypertrophic adaptations in trained persons [24] and where similar adaptations are attainable with both heavier-and lighter-loads [19,50] and both equipment-and bodyweight-based exercise [30,32]. ...
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Background Virtual personal training might represent an uncomplicated, accessible, and time-efficient approach to supervised strength training, particularly under government-imposed lockdown or closure of fitness facilities. However, there appears a dearth of literature evaluating the efficacy of virtual personal training. Methods The present project considered two studies considering supervised virtual strength training. Study 1 considered trained participants being supervised one-to-one through traditional resistance exercise sessions in a strength training studio (STUD), compared to a virtual personal training protocol performed using bodyweight resistance exercises (VIRT). This study utilized a crossover design whereby male (n=13) and female (n=7) participants were tested for body composition using BodPod, and strength for bench press, leg press, and high-row exercises. Participants were then randomly assigned to 3-weeks of VIRT or 3-weeks of STUD training. Following each 3-week training period, participants had a 1-week period without training whereby mid-intervention testing occurred, after which participants then completed the alternate training intervention. For study 2, we surveyed the client base of a chain of training facilities who had begun offering virtual personal training during lockdown to explore their views on this approach. Results Strength and body composition changes were similar between groups, however for neither condition did results surpass the smallest meaningful change. The remaining survey data suggests that supervised virtual resistance training yields similar perceptions of effort, motivation, enjoyment, and supervision quality, compared to traditional supervised studio training. Conclusion Based on the current data, it appears that short-term supervised virtual resistance training is as efficacious as traditional supervised studio-based resistance training.
... However, in addition to the strength and associated health improvements, RT is often performed for aesthetic purposes such as hypertrophy 8 and fat loss 9 . Recent research has suggested that muscle hypertrophy increases are similar whether training with heavier-(>60% 1-repetition maximum; RM) or lighter-(<60% 1RM) loads 10 , and indeed, that adaptations are more likely a product of effort rather than external load 11 . However, whilst RT has been shown to increase metabolic rate 12 , the evidence remains unclear as to the best loading strategies and repetition ranges to optimise energy expenditure (EE), and concurrently, fat loss. ...
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... As such, ratings of perceived exertion (RPE) may provide a more practical method to prescribe intensity [52]. An alternative approach is to prescribe RE intensity using an effort-based approach [53,54]. ...
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... Considering the popularity of online training (Thompson, 2021) and that over lockdown in particular it was those already active who continued to participate in exercise (Strain et al., 2022) to date, there appears no research considering the efficacy of virtual personal training in trained males and females . Furthermore, whilst evidence has supported that strength and muscle mass adaptations are similar for both heavier-and lighter-loads (Fisher, et al. 2020;Schoenfeld, et al. 2021), virtual personal training often relies on trainees utilising bodyweight exercise or what weights and equipment they may have available at home. During lockdown, despite most people performing resistance training at home, most utilised higher repetition ranges suggesting the use of lighter loads . ...
Preprint
Full-text available
Background: Virtual personal training might represent an uncomplicated, accessible, and time-efficient approach to supervised strength training, particularly under government-imposed lockdown or closure of fitness facilities. However, there appears a dearth of literature evaluating the efficacy of virtual personal training. Methods: The present study considered trained participants being supervised one-to-one through traditional resistance exercise sessions in a strength training studio (STUD), compared to a virtual personal training protocol performed using bodyweight resistance exercises (VIRT). The study utilized a crossover design whereby male (n=13) and female (n=7) participants were tested for body composition using BodPod, and strength for bench press, leg press, and high-row exercises. Participants were then randomly assigned to 3-weeks of VIRT or 3-weeks of STUD training. Following each 3-week training period, participants had a 1-week washout period without training whereby mid-intervention testing occurred, after which participants then completed the alternate training intervention. Further, we surveyed the client base of a chain of training facilities who had begun offering virtual personal training during lockdown to explore their views on this approach. Results: Strength and body composition changes were similar between groups, however for neither condition did results surpass the smallest meaningful change. The remaining survey data suggests that supervised virtual resistance training yields similar perceptions of effort, motivation, enjoyment, and supervision quality, compared to traditional supervised studio training. Conclusion: Based on the current data, it appears that short-term supervised virtual resistance training is as efficacious as traditional supervised studio-based resistance training.
... The aim of including the AMRAP group was to explore the effect of moderate-load higher repetition "daily max" sets on 1RM strength, to understand whether PL athletes can utilize lighter loads when training with a METD approach. As previously mentioned, utilizing light to moderate loads can elicit significant strength increases, but when assessing strength via a 1RM test, heavier loads may result in greater strength increases (Lasevicius et al., 2018;Fisher et al., 2020;Schoenfeld et al., 2021). Interestingly, despite the AMRAP group performing more training volume than the MAX+boff group, they were unable to attain similar strength increases as the MAX+boff group. ...
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The aim of this multi-experiment paper was to explore the concept of the minimum effective training dose (METD) required to increase 1-repetition-maximum (1RM) strength in powerlifting (PL) athletes. The METD refers to the least amount of training required to elicit meaningful increases in 1RM strength. A series of five studies utilising mixed methods, were conducted using PL athletes & coaches of all levels in an attempt to better understand the METD for 1RM strength. The studies of this multi-experiment paper are: an interview study with elite PL athletes and highly experienced PL coaches (n = 28), an interview and survey study with PL coaches and PL athletes of all levels (n = 137), two training intervention studies with intermediate-advanced PL athletes (n = 25) and a survey study with competitive PL athletes of different levels (n = 57). PL athletes looking to train with a METD approach can do so by performing ∼3-6 working sets of 1-5 repetitions each week, with these sets spread across 1-3 sessions per week per powerlift, using loads above 80% 1RM at a Rate of Perceived Exertion (RPE) of 7.5-9.5 for 6-12 weeks and expect to gain strength. PL athletes who wish to further minimize their time spent training can perform autoregulated single repetition sets at an RPE of 9-9.5 though they should expect that strength gains will be less likely to be meaningful. However, the addition of 2-3 back-off sets at ∼80% of the single repetitions load, may produce greater gains over 6 weeks while following a 2-3-1 squat-bench press-deadlift weekly training frequency. When utilizing accessory exercises in the context of METD, PL athletes typically utilize 1-3 accessory exercises per powerlift, at an RPE in the range of 7-9 and utilize a repetition range of ∼6-10 repetitions.
... Among other variables, movement tempo is an acute resistance-training variable that can be manipulated to potentially optimize maximal strength development. Strength improvements following resistance training tend to be most pronounced when the method of assessment is specific to the type of muscle action mode used in training [67], when heavier loads are used during training [68], and when the test is specific to the muscle actions trained [2,[69][70][71][72]. Compared to changes in muscle size, changes in strength appear to be largely dependent on the principle of specificity [71,73]. ...
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Hypertrophy and strength are two common long-term goals of resistance training that are mediated by the manipulation of numerous variables. One training variable that is often neglected but is essential to consider for achieving strength and hypertrophy gains is the movement tempo of particular repetitions. Although research has extensively investigated the effects of different intensities, volumes, and rest intervals on muscle growth, many of the present hypertrophy guidelines do not account for different movement tempos, likely only applying to volitional movement tempos. Changing the movement tempo during the eccentric and concentric phases can influence acute exercise variables, which form the basis for chronic adaptive changes to resistance training. To further elaborate on the already unclear anecdotal evidence of different movement tempos on muscle hypertrophy and strength development, one must acknowledge that the related scientific research does not provide equivocal evidence. Furthermore, there has been no assessment of the impact of duration of particular movement phases (eccentric vs. concentric) on chronic adaptations, making it difficult to draw definitive conclusions in terms of resistance-training recommendations. Therefore, the purpose of this review is to explain how variations in movement tempo can affect chronic adaptive changes. This article provides an overview of the available scientific data describing the impact of movement tempo on hypertrophy and strength development with a thorough analysis of changes in duration of particular phases of movement. Additionally, the review provides movement tempo-specific recommendations as well real training solutions for strength and conditioning coaches and athletes, depending on their goals.
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Public health guidelines for resistance training emphasize a minimal effective dose intending for individuals to engage in these behaviors long term. However, few studies have adequately examined the longitudinal time-course of strength adaptations to resistance training. Purpose: The aim of this study was to examine the time-course of strength development from minimal-dose resistance training in a large sample through retrospective training records from a private international exercise company. Methods: Data were available for analysis from 14,690 participants (60% female; aged 48 ± 11 years) having undergone minimal-dose resistance training (1x/week, single sets to momentary failure of six exercises) up to 352 weeks (~6.8 years) in length. Linear-log growth models examined strength development over time allowing random intercepts and slopes by participant. Results: All models demonstrated a robust linear-log relationship with the first derivatives (i.e., changes in strength with time) trending asymptotically such that by ~1-2 years strength had practically reached a "plateau." Sex, bodyweight, and age had minimal interaction effects. However, substantial strength gains were apparent; approximately ~30-50% gains over the first year reaching ~50-60% of baseline 6 years later. Conclusion: It is unclear if the "plateau" can be overcome through alternative approaches, or whether over the long-term strength gains differ. Considering this, our results support public health recommendations for minimal-dose resistance training for strength adaptations in adults.
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The prescription of resistance exercise often involves administering a set number of repetitions to be completed at a given relative load. While this accounts for individual differences in strength, it neglects to account for differences in local muscle endurance and may result in varied responses across individuals. One way of potentially creating a more homogenous stimulus across individuals involves performing resistance exercise to volitional failure, but this has not been tested and was the purpose of the present study. Individuals completed 2 testing sessions to compare repetitions, ratings of perceived exertion (RPE), muscle swelling and fatigue responses to arbitrary repetition (SET) vs. failure (FAIL) protocols using either 60% or 30% one-repetition maximum. Statistical analyses assessed differences in the variability between protocols. Forty-six individuals (25 females and 21 males) completed the study. There was more variability in the number of repetitions completed during FAIL when compared to SET protocols. Performing the 60% 1RM condition to failure appeared to reduce the variability in muscle swelling (average variance: 60%-SET = .034, 60%-FAIL = .023) and RPE (average variance: 60%-SET = 4.0, 60%-FAIL = 2.5), but did not alter the variability in muscle fatigue. No differences in variability were present between the SET-30% and FAIL-30% protocols for any of the dependent variables. Performing resistance exercise to failure may result in a more homogenous stimulus across individuals, particularly when using moderate to high exercise loads. The prescription of resistance exercise should account for individual differences in local muscle endurance to ensure a similarly effective stimulus across individuals.Highlights There is a large variance in the number of repetitions individuals can complete even when exercising with the same relative load.Ratings of perceived exertion and muscle swelling responses become more homogenous when exercising to volitional failure as compared to using performing a set number of repetitions, particularly when moderate to higher loads are used.The prescription of exercise should take into consideration the individual's local muscle endurance as opposed to choosing an arbitrary number of repetitions to be completed at a given relative load.
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Objectives Muscles dominant in type I muscle fibres, such as the lumbar extensors, are often trained using lighter loads and higher repetition ranges. However, literature suggests that similar strength adaptations can be attained by the use of both heavier- (HL) and lighter-load (LL) resistance training across a number of appendicular muscle groups. Furthermore, LL resistance exercise to momentary failure might result in greater discomfort. Design The aims of the present study were to compare strength adaptations, as well as perceptual responses of effort (RPE-E) and discomfort (RPE-D), to isolated lumbar extension (ILEX) exercise using HL (80% of maximum voluntary contraction; MVC) and LL (50% MVC) in healthy males and females. Methods Twenty-six participants ( n = 14 males, n = 12 females) were divided in to sex counter-balanced HL (23 ± 5 years; 172.3 ± 9.8 cm; 71.0 ± 13.1 kg) and LL (22 ± 2 years; 175.3 ± 6.3 cm; 72.8 ± 9.5 kg) resistance training groups. All participants performed a single set of dynamic ILEX exercise 1 day/week for 6 weeks using either 80% (HL) or 50% (LL) of their MVC to momentary failure. Results Analyses revealed significant pre- to post-intervention increases in isometric strength for both HL and LL, with no significant between-group differences ( p > 0.05). Changes in strength index (area under torque curves) were 2,891 Nm degrees 95% CIs [1,612–4,169] and 2,865 Nm degrees 95% CIs [1,587–4,144] for HL and LL respectively. Changes in MVC were 51.7 Nm 95% CIs [24.4–79.1] and 46.0 Nm 95% CIs [18.6–73.3] for HL and LL respectively. Mean repetitions per set, total training time and discomfort were all significantly higher for LL compared to HL (26 ± 8 vs. 8 ± 3 repetitions, 158.5 ± 47 vs. 50.5 ± 15 s, and 7.8 ± 1.8 vs. 4.8 ± 2.5, respectively; all p < 0.005). Conclusions The present study supports that that low-volume, low-frequency ILEX resistance exercise can produce similar strength increases in the lumbar extensors using either HL or LL. As such personal trainers, trainees and strength coaches can consider other factors which might impact acute performance (e.g. effort and discomfort during the exercise). This data might prove beneficial in helping asymptomatic persons reduce the risk of low-back pain, and further research, might consider the use of HL exercise for chronic low-back pain symptomatic persons.
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Purpose: The purpose of this study was to evaluate muscular adaptations between low-, moderate-, and high-volume resistance training (RT) protocols in resistance-trained men. Methods: Thirty-four healthy resistance-trained men were randomly assigned to 1 of 3 experimental groups: a low-volume group (1SET) performing 1 set per exercise per training session (n = 11); a moderate-volume group (3SET) performing 3 sets per exercise per training session (n = 12); or a high-volume group (5SET) performing 5 sets per exercise per training session (n = 11). Training for all routines consisted of three weekly sessions performed on non-consecutive days for 8 weeks. Muscular strength was evaluated with 1 repetition maximum (RM) testing for the squat and bench press. Upper-body muscle endurance was evaluated using 50% of subjects bench press 1RM performed to momentary failure. Muscle hypertrophy was evaluated using B-mode ultrasonography for the elbow flexors, elbow extensors, mid-thigh and lateral thigh. Results: Results showed significant pre-to-post intervention increases in strength and endurance in all groups, with no significant between-group differences. Alternatively, while all groups increased muscle size in most of the measured sites from pre-to-post intervention, significant increases favoring the higher volume conditions were seen for the elbow flexors, mid-thigh, and lateral thigh. Conclusion: Marked increases in strength and endurance can be attained by resistance-trained individuals with just three, 13-minute weekly sessions over an 8-week period, and these gains are similar to that achieved with a substantially greater time commitment. Alternatively, muscle hypertrophy follows a dose-response relationship, with increasingly greater gains achieved with higher training volumes.
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Background There is a lack of research considering acute fatigue responses to high- and low-load resistance training as well as the comparison between male and female responses. Furthermore, limited studies have considered fatigue response testing with the inclusion of perceptions of discomfort and exertion. Methods The present study included males (n = 9; 23.8 ± 6.4 years; 176.7 ± 6.2 cm; 73.9 ± 9.3 kg) and females (n = 8; 21.3 ± 0.9 years; 170.5 ± 6.1 cm; 65.5 ± 10.8 kg) who were assessed for differences in fatigue (i.e., loss of torque at maximal voluntary contraction (MVC)) immediately following isolated lumbar extension (ILEX) exercise at heavy- (HL) and light-(LL) loads (80% and 50% MVC, respectively). Participants also reported perceptual measures of effort (RPE-E) and discomfort (RPE-D) between different resistance training protocols. Results Analysis of variance revealed significantly greater absolute and relative fatigue following LL compared to HL conditions (p < 0.001). Absolute fatigue significantly differed between males and females (p = 0.012), though relative fatigue was not significantly different (p = 0.160). However, effect sizes for absolute fatigue (HL; Males = −1.84, Females = −0.83; LL; Males = −3.11, Females = −2.39) and relative fatigue (HL; Males = −2.17, Females = −0.76; LL; Males = −3.36, Females = −3.08) were larger for males in both HL and LL conditions. RPE-E was maximal for all participants in both conditions, but RPE-D was significantly higher in LL compared to HL (p < 0.001) with no difference between males and females. Discussion Our data suggests that females do not incur the same degree of fatigue as males following similar exercise protocols, and indeed that females might be able to sustain longer exercise duration at the same relative loads. As such females should manipulate training variables accordingly, perhaps performing greater repetitions at a relative load, or using heavier relative loads than males. Furthermore, since lighter load exercise is often prescribed in rehabilitation settings (particularly for the lumbar extensors) it seems prudent to know that this might not be necessary to strengthen musculature and indeed might be contraindicated to avoid the increased fatigue and discomfort associated with LL exercise.
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Hamstring strain injuries are endemic in running-based sports. Given the economic and performance implications of these injuries, a significant body of research has emerged in recent years in an attempt to identify risk factors and develop or optimise injury prevention strategies. Surveys of injury prevention practices among medical and conditioning staff in elite sport suggest that many sporting clubs invest significant efforts in eccentric hamstring conditioning and lumbo-pelvic or trunk stability programmes. The purpose of this narrative review was to critically evaluate the evidence underpinning these practices. Single-exercise eccentric training interventions have proven effective in the prevention of primary and recurrent hamstring strains, when compliance is adequate. However, despite its almost universal acceptance, the authors are aware of only one, very recent, prospective risk factor study examining the effect of lumbo-pelvic motion during sprinting on hamstring injury risk. Furthermore, the interventions exploring the effect of lumbo-pelvic training on hamstring injury rates have not measured stability in any way. An improved understanding of the evidence underpinning commonly employed hamstring injury prevention practices may enable clinicians and coaches to better prioritise effective strategies in the increasingly complex environment of elite sport.
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Purpose: To examine the effect of high-intensity interval training (HIIT) compared to volume-matched moderate-intensity continuous training (CONT) on muscle pain tolerance and high-intensity exercise tolerance. Methods: Twenty healthy adults were randomly assigned (1:1) to either 6 weeks of HIIT [6-8 × 5 min at halfway between lactate threshold and maximal oxygen uptake (50%Δ)] or volume-matched CONT (~60-80 min at 90% lactate threshold) on a cycle ergometer. A tourniquet test to examine muscle pain tolerance and two time to exhaustion (TTE) trials at 50%Δ to examine exercise tolerance were completed pre- and post-training; the post-training TTE trials were completed at the pre-training 50%Δ (same absolute-intensity) and the post-training 50%Δ (same relative-intensity). Results: HIIT and CONT resulted in similar improvements in markers of aerobic fitness (all P ≥ 0.081). HIIT increased TTE at the same absolute- and relative-intensity as pre-training (148 and 43%, respectively) to a greater extent than CONT (38 and -4%, respectively) (both P ≤ 0.019). HIIT increased pain tolerance (41%, P < 0.001), whereas CONT had no effect (-3%, P = 0.720). Changes in pain tolerance demonstrated positive relationships with changes in TTE at the same absolute- (r = 0.44, P = 0.027) and relative-intensity (r = 0.51, P = 0.011) as pre-training. Conclusion: The repeated exposure to a high-intensity training stimulus increases muscle pain tolerance, which is independent of the improvements in aerobic fitness induced by endurance training, and may contribute to the increase in high-intensity exercise tolerance following HIIT.
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The purpose of this paper was to conduct a systematic review of the current body of literature and a meta-analysis to compare changes in strength and hypertrophy between low- versus high-load resistance training protocols. Searches of PubMed/MEDLINE, Cochrane Library and Scopus were conducted for studies that met the following criteria: 1) an experimental trial involving both low- (≤60% 1 RM) and high- (>60% 1 RM) load training; 2) with all sets in the training protocols being performed to momentary muscular failure; 3) at least one method of estimating changes in muscle mass and/or dynamic, isometric or isokinetic strength was used; 4) the training protocol lasted for a minimum of 6 weeks; 5) the study involved participants with no known medical conditions or injuries impairing training capacity. A total of 21 studies were ultimately included for analysis. Gains in 1RM strength were significantly greater in favor of high- versus low-load training, while no significant differences were found for isometric strength between conditions. Changes in measures of muscle hypertrophy were similar between conditions. The findings indicate that maximal strength benefits are obtained from the use of heavy loads while muscle hypertrophy can be equally achieved across a spectrum of loading ranges.
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The generality of strength suggests that a "strong" individual will typically exhibit higher values of strength across a wide range of strength tasks for a given muscle relative to their weaker counterpart. This concept is often extended to adaptation, suggesting that increasing strength on a given movement or strength task with a given muscle should reflect an increase in other movements or tasks using that same muscle. The concept of a generality of strength adaptation appears less supported in the literature. Objective: To elaborate on recommendations for strength assessment, providing a focus on the "generality of strength" and the "generality of strength adaptation." Design & Methods: We reviewed the literature on a generality of strength. In addition, we examined the resistance training literature to provide evidence and discussion on a generality of strength adaptation. Results/Conclusions: The generality of strength adaptation, even across strength skills using the same muscle on related movements seems quite low. Although some studies show a weak generality of strength adaptation and others show no generality of strength adaptation, it appears that increases in strength diminish as the strength assessment becomes farther removed from the actual training stimulus. (Journal of Trainology 2019;8:5-8)
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New findings: What is the topic for this review? The dichotomisation of continuous-level physiological measurements into "responders" and "non-responders", when interventions/treatments are examined in robust parallel-group studies What advances does it highlight? Sample responder counts are biased by pre-to-post within-subjects variability. Sample differences in counts may be explained wholly by differences in mean response, even without individual response heterogeneity, and even if test-retest measurement error informs the choice of response threshold. A less biased and more informative approach employs the SD of individual responses to estimate the chance a new person from the population of interest will be a responder. Abstract: As a follow-up to our 2015 review, we cover more issues on the topic of "response heterogeneity", which we define as clinically-important individual differences in the physiological responses to the same treatment or intervention that cannot be attributed to random within-subjects variability. We highlight various pitfalls with the common practice of counting the number of "responders", "non-responders" and "adverse responders" in samples that have been given certain treatments/interventions for research purposes. We focus on the classical parallel-group randomised controlled trial (RCT) and assume typical good practice in trial design. We show that sample responder counts are biased because individuals differ in terms of pre-to-post within-subjects random variability in the study outcome(s) and not necessarily treatment response. Ironically, sample differences in responder counts may be explained wholly by sample differences in mean response, even if there is no response heterogeneity at all. Sample comparisons of responder counts also have relatively low statistical precision. These problems do not depend on how the response threshold has been selected, e.g. on the basis of a measurement error statistic, and are not rectified fully by the use of confidence intervals for individual responses in the sample. The dichotomisation of individual responses in a research sample is fraught with pitfalls. Less biased approaches for estimating the proportion of responders in a population of interest are now available. Importantly, these approaches are based on the standard deviation for true individual responses, directly incorporating information from the control group. This article is protected by copyright. All rights reserved.
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The capacity to sustain high-intensity aerobic exercise is essential for endurance performance. Therefore, it is important to understand what is the factor limiting time to exhaustion (TTE) in healthy and fit adults. In Study 1, maximal voluntary cycling power (MVCP) was measured in 11 volunteers before and immediately after a high-intensity TTE test on cycle ergometer. Cadence was 60 rpm in both the MVCP and TTE tests. Despite a 35% loss in MVCP, power produced during the final MVCP test (mean +/- SD 469 +/- 111W) was significantly higher than the power required by the TTE test (269 +/- 55 W) (P < 0.001). In Study 2, 12 participants performed a cold pressor test (CPT) to the limit of tolerance followed by a high-intensity TTE test on cycle ergometer. Ratings of pain unpleasantness (RPU) during the TTE test were anchored to the unpleasantness of pain experienced during the CPT. On average, the RPU was 9.7 +/- 0.4 at completion of the CPT and 5.0 +/- 0.9 at exhaustion during the TTE test. The difference between these two ratings of pain unpleasantness was statistically significant (P< 0.001). In both Studies 1 and 2, the slope of the rating of perceived exertion (RPE) during the TTE test correlated significantly with TTE (r = –0.75 and –0.83, P < 0.01). Results of this two-part investigation suggest that perception of effort, rather than severe locomotor muscle fatigue or intolerably unpleasant muscle pain, is the cardinal exercise stopper during high-intensity aerobic exercise.
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Objectives: To assess the prevalence of non-responders to different tests and to compare the effects of different resistance training (RT) volumes on muscle strength, anthropometric and functional performance of older women. Methods: Three hundred seventy six women performed 12weeks of RT with either low or high volume (LV, 71.29±5.77years and HV 69.73±5.88years, respectively). Both groups performed the same exercises, and all parameters were held constant except for the number of sets performed per week. LV performed 8-12 for upper and 4-6 for lower body, while HV performed 16-20 and 8-10, respectively. Before and after the training period, the participants were tested for bench press and leg press 1RM, 30-s chair stand, 30-s arm curl, six-minute walk test, sit and reach, body weight and waist circumference. Results: Both groups significantly improved in all strength and functional tests and reduced their body weight and waist circumference. ANOVA revealed higher gains in the leg press 1RM, 30-s arm curls and 6-min walk test for the HV group and higher increases in the results of the sit and reach test for the LV group. However, the differences were negligible and may be attributable to a type I error due to the large sample size. Non-responsiveness was not apparent in any subject, as a positive response on at least one outcome was present in every participant. Conclusions: Our results suggest that RT, even at low volume, improves waist circumference, muscle strength and physical function in the older population, with no evidence of non-responsiveness. Therefore, we should not be restrictive in prescribing this type of exercise to this population.