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

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 ReviewResults: 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.(Journal of Trainology 2020;9:1-8)

Impact of resistance training status on trunk muscle activation in a fatiguing set of heavy back squats

“…They had fewer participants (Trained: n = 9 vs 19, Untrained: n = 7 vs 21), who were significantly stronger according to mean squat 1RM, (Trained: 184 vs 156 kg, Untrained: 120 vs 96 kg). The contributes to the growing challenge directed at the repetition maximum continuum (Haff and Triplett 2016 ; Fisher et al 2020 ), specifically the accepted relationship between load calculated as a percentage 1RM and the repetition maximum method of load assignment (Hoeger Werner et al 1990 ; Shimano et al 2006 ). Our data also support evidence that training status does not influence the relationship between the relative 1RM and RM method of load calculation in the squat exercise (Hoeger Werner et al 1990 ; Shimano et al 2006 ; Mann et al 2010 ).…”

A low caffeine dose improves maximal strength, but not relative muscular endurance in either heavier-or lighter-loads, or perceptions of effort or discomfort at task failure in females

“…Previous studies comparing lighter-and heavier-load exercise to momentary failure have reported similar values for effort, but higher values for discomfort for a lighter load condition Stuart et al, 2018). Indeed, improvements in measures of relative muscular endurance have been speculated to be in part due to greater tolerance of perceived discomfort (Fisher et al, 2020). Thus, any performance enhancement in lighter-compared to heavier-load exercise may be due to effects upon perceptual variables.…”

“…Sabblah, Dixon & Bottoms (2015) found that, though not significant, any effect on relative muscular endurance at 40% 1RM appeared to be larger in males compared with females. It is worth considering however that with increases in strength resultant from interventions such as resistance training, relative muscular endurance typically does not change (Fisher et al, 2020). In previous studies, strength is normally measured using 1RM on a separate day to the placebo and caffeine conditions and so where there are changes this may be due to increased strength from supplementation resulting in the load used for muscular endurance testing being relatively less.…”

“…It has also been shown that caffeine produces analgesic effects and thus may improve performance similarly by reducing pain perception allowing higher exercise intensities to be produced at the same level of pain perception, or again deterring task disengagement due to reaching maximum tolerable pain levels (Motl, O'Connor & Dishman, 2003;Motl et al, 2006;Astorino et al, 2011;Duncan et al, 2013). Indeed, relative muscular endurance typically does not change with interventions including resistance training, but where it does it has been speculated this may be due to reductions in perceived discomfort (Fisher et al, 2020). However, both the perceived effort and perceived pain reducing effects of caffeine have only been shown with higher doses (4-10 mg•kg −1 ).…”

The Influence of Movement Tempo During Resistance Training on Muscular Strength and Hypertrophy Responses: A Review

“…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].…”