A comparison of traditional and novel metrics to quantify resistance training

The intensity of a resistance exercise session can be quantified by the work rate of exercise

PURPOSE

Athletes regularly perform resistance training, yet it is unknown how best to monitor its intensity. This study compared different resistance exercise intensity metrics to determine their sensitivity to manipulating work rate (via altering inter-set rest and load).

METHODS

Following baseline testing for 10- and 3-repetition maximum (RM; squat and bench press), fourteen trained participants completed four volume-matched protocols in a randomised order: 3x10 with 85% 10RM, 60 s rest (3x1060s); 3x10 with 85% 10RM, 180 s (3x10180s); 8x3 with 85% 3RM, 120 s (8x3120s); 8x3 with 85% 3RM, 300 s (8x3300s). Internal intensity was quantified via rate of oxygen consumption ([Formula: see text]), heart rate, blood lactate concentration, and rating of perceived exertion (RPE). External intensity was assessed via previously developed "Training-Intensity" (TI) and "Intensity-Index" (II) metrics, and from exercise work rate (expressed as kg∙min-1 and joules∙min-1).

RESULTS

Internal intensity and work-rate metrics were highest for 3x1060s, followed by 3x10180s, 8x3120s and 8x3300s (p≤0.027). TI and II were higher for 8x3 than 3x10 protocols (p<0.001), but not different within these configurations. Internal intensity measures were more strongly correlated with work rate (r = 0.37-0.96) than TI and II (r = -0.42-0.33) metrics.

CONCLUSIONS

Work rate corroborated objective internal intensity metrics during resistance exercise, with the highest work rate session (3x1060s) also eliciting greater RPE scores than other protocols. In contrast, the TI and II did not agree with other intensity measures, likely because they do not consider rest periods. Practitioners can plan for the physiological and perceptual demands of resistance training by estimating work rate.

Effect of High-Intensity Resistance Training Versus Endurance Training on Irisin and Adipomyokine Levels in Healthy Individuals: An 8-Week Interventional Study

Background: Irisin and adipomyokine are proteins secreted by the body during exercise and exhibit potential therapeutic effects for chronic disorders. Gaining insights into how high-intensity resistance training and endurance training influence irisin and adipomyokine secretion could shed light on optimizing exercise regimens for potential therapeutic applications. Such knowledge could pave the way for personalized exercise prescriptions and contribute to the development of novel treatments for chronic conditions, enhancing overall health and well-being. Objectives: To investigate the effects of high-intensity resistance training (HIRT) and endurance training on irisin and adipomyokine levels in healthy individuals. Methods: An 8-week interventional comparative study was conducted at Nimra Institute of Medical Sciences, Andhra Pradesh, India. One hundred healthy male individuals aged 21 to 35 were divided into two groups: HIRT and endurance. The HIRT group performed high-intensity resistance training, while the endurance group performed endurance training. Ethical approval was obtained, and baseline and post-intervention values of the participants were recorded and analyzed using SPSS software. Results: After 8 weeks, irisin levels were significantly elevated in the HIRT group (167.39±11.27) compared to the endurance group (155.39±11.28). A positive correlation was observed between skeletal muscle and irisin levels in both the HIRT group (χ2-16.38; p=0.04) and the endurance group (χ2-18.36; p=0.01). Additionally, TNF-α (HIRT: 81.47±4.02 and Endurance: 61.19±4.00) and interleukin-6 (IL-6) (HIRT: 46.84±4.46 and Endurance: 36.15±3.89) levels significantly increased in the HIRT group. However, there was no significant change in leptin levels in either group (HIRT: 3.75±0.58 0.58 and 4.15±0.58). Conclusion: The findings of this study indicate that HIRT is more effective in increasing irisin levels compared to endurance training. However, the notable elevation of IL-6 and TNF-α in the HIRT group raises concerns about potential chronic inflammation. To optimize outcomes, a combined approach, coupling HIRT and endurance training, may be beneficial. Additionally, the results emphasize the significance of skeletal muscle as a primary source of irisin secretion, implying that increased muscle contraction contributes to higher irisin release even in healthy individuals. These insights can guide exercise prescriptions and potentially enhance therapeutic strategies for chronic disorders.

Influence of different recovery intervals on time under tension, total training volume, and fatigue index in horizontal bench press exercise in young male wrestling athletes

BACKGROUND

The recovery interval (RI) seems to be a variable closely related to the training volume since it can determine the performance after this rest time. This study investigated the influence of different recovery intervals on time under tension (TUT), total training volume (TTV), and Fatigue Index (FI) in the horizontal bench press exercise.

METHODS

Eighteen male wrestling athletes underwent three visits: 1st) performed the 10-repetition maximum (10RM) test; 2nd and 3rd) performed 5 sets of up to 10 repetitions with 1 minute (RI1) and 3 minutes (RI3) of passive RI with randomized entry. TUT, number of repetitions, TTV and FI data were collected or calculated.

RESULTS

TUT was lower in sets 5 (P<0.001) for RI1 when compared to RI3, with no significant difference for the other 4 sets. The number of repetitions for RI1 was lower when compared to RI3 in sets 3 (P=0.018), 4 (P=0.023), and 5 (P<0.001), with no significant difference in sets 1 and 2. The FI was significantly higher for RI1 (P<0.001); however, TTV was significantly higher for RI3 (P=0.007).

CONCLUSIONS

Different RI influenced the TUT and the number of repetitions along 5 sets in the horizontal bench press exercise. Moreover, these two variables showed different behavior when compared under the same condition (RI1 or RI3), especially after the third set. Using longer RI demonstrated a greater ability to maintain TTV and less negative effect of fatigue in young male wrestling athletes.

Drop-Set Resistance Training versus Pyramidal and Traditional Sets Elicits Greater Psychophysiological Responses in Men

We compared the effects of resistance training (ResisT) to pyramidal and traditional weightlifting sets on men's psychophysiological responses. In a randomized crossover design, 24 resistance-trained males performed drop-set, descending pyramid, and traditional ResisT in the barbell back squat, 45° leg press, and seated knee extension. We assessed participants' rating of perceived exertion (RPE) and feelings of pleasure/displeasure (FPD) at the end of each set and at 10, 15, 20, and 30 minutes post-session. No differences were detected across ResisT Methods in total training volume (p = 0.180). Post hoc comparisons revealed that drop-set training elicited higher RPE (M 8.8 SD 0.7 arbitrary units) and lower FPD (M -1.4 SD 1.5 arbitrary units) values compared to descending pyramid (M Set RPE 8.0 SD 0.9 arbitrary units and M Set FPD 0.4 SD 1.6 arbitrary units) and traditional set (M Set RPE 7.5 SD 1.1 arbitrary units and M Set FPD 1.3 SD 1.2 arbitrary units) schemes (p < 0.05). In addition, drop-set training elicited higher session RPE (M 8.1 SD 0.8 arbitrary units) and lower session FPD (M 0.2 SD 1.4 arbitrary units) values than descending pyramid and traditional ResisT (p < 0.001). Similarly, descending pyramid training elicited higher session RPE (M 6.6 SD 0.9 arbitrary units) and lower session FPD (M 1.2 SD 1.4 arbitrary units) than traditional set (M Session RPE 5.9 SD 0.8 arbitrary units and M Session FPD 1.5 SD 1.2 arbitrary units) training (p = 0.015). No differences were found in the temporality of post-session metrics, suggesting that testing 10 and 15 minutes post-ResisT was sufficient to assess session RPE (p = 0.480) and session FPD (p = 0.855), respectively. In conclusion, even with similar total training volume, drop-set training elicited more pronounced psychophysiological responses than either pyramidal or traditional ResisT in resistance-trained males.

Acute Effects of Different Set Configurations on Neuromuscular, Metabolic, and Perceptual Responses in Young Women

We compared neuromuscular, metabolic, and perceptual responses between different resistance training configurations in young women. In a counterbalanced randomized order, 13 young women performed the following protocols in separate sessions (sets x repetitions): traditional (TRAD): 5x10, 90-s of rest interval between sets; more frequent and shorter total rest (FSR): 10x5, 30-s of rest interval between sets. The sessions were composed of leg press exercise with the same intensity. Force (maximum voluntary isometric contraction [MVIC]) and metabolic (lactate concentration) responses were measured pre- and post-resistance training sessions. The rating of perceived exertion (RPE) was measured after each set. The internal training load was calculated using the session-RPE method. There was a significant reduction in the MVIC only after TRAD configuration (Effect size [ES] = 0.36). The lactate concentration increased in both conditions but was higher after TRAD (ES = 2.81) than FSR (ES = 1.23). The RPE has progressively increased in both configurations. On the other hand, the internal training load was lower in the FSR configuration. From our findings, we suggest that more frequent and shorter total rest is an effective strategy for maintaining the ability to produce force, generating less metabolic stress and lower perceived internal load in young women.

Manipulating the Resistance Training Volume in Middle-Aged and Older Adults: A Systematic Review with Meta-Analysis of the Effects on Muscle Strength and Size, Muscle Quality, and Functional Capacity

BACKGROUND

Effective manipulation of the acute variables of resistance training is critical to optimizing muscle and functional adaptations in middle-aged and older adults. However, the ideal volume prescription (e.g., number of sets performed per exercise) in middle-aged and older adults remains inconclusive in the literature.

OBJECTIVE

The effects of single versus multiple sets per exercise on muscle strength and size, muscle quality, and functional capacity in middle-aged and older adults were compared. Moreover, the effects of single versus multiple sets per exercise on muscular and functional gains were also examined, considering the influence of training duration.

METHODS

Randomized controlled trials and non-randomized controlled trials comparing single versus multiple sets per exercise on muscle strength, muscle size, muscle quality, or functional capacity in middle-aged and older adults (aged ≥ 50 years) in the PubMed/MEDLINE, Web of Science, and Scopus databases (01/09/2021, updated on 15/05/2022) were identified. A random-effects meta-analysis was used.

RESULTS

Fifteen studies were included (430 participants; 93% women; age 57.9-70.1 years). Multiple sets per exercise produced a greater effect than single sets on lower-limb strength (standardized mean difference [SMD] = 0.29; 95% confidence interval [CI] 0.07-0.51; mean difference [MD] = 1.91 kg; 95% CI 0.50-3.33) and muscle quality (SMD = 0.40; 95% CI 0.05-0.75) gains. There were no differences between single versus multiple sets per exercise for upper-limb strength (SMD = 0.13; 95% CI - 0.14 to 0.40; MD = 0.11 kg; 95% CI - 0.52 to 0.75), muscle size (SMD = 0.15; 95% CI - 0.07 to 0.37), and functional capacity (SMD = 0.01; 95% CI - 0.47 to 0.50) gains. In addition, there were no differences between single versus multiple sets on muscle strength and size gains for training durations ≤ 12 weeks or > 12 weeks.

CONCLUSIONS

Multiple sets per exercise produced greater lower-limb strength and muscle quality gains than single sets in middle-aged and older adults, although the magnitude of the difference was small. In contrast, single sets per exercise were sufficient to improve upper-limb strength, muscle size, and functional capacity in these populations. Despite these findings, researchers should conduct future high-quality, pre-registered, and blinded randomized controlled trials to strengthen the scientific evidence on this topic.

The role of the neural stimulus in regulating skeletal muscle hypertrophy

Resistance training is frequently performed with the goal of stimulating muscle hypertrophy. Due to the key roles motor unit recruitment and mechanical tension play to induce muscle growth, when programming, the manipulation of the training variables is oriented to provoke the correct stimulus. Although it is known that the nervous system is responsible for the control of motor units and active muscle force, muscle hypertrophy researchers and trainers tend to only focus on the adaptations of the musculotendinous unit and not in the nervous system behaviour. To better guide resistance exercise prescription for muscle hypertrophy and aiming to delve into the mechanisms that maximize this goal, this review provides evidence-based considerations for possible effects of neural behaviour on muscle growth when programming resistance training, and future neurophysiological measurement that should be tested when training to increase muscle mass. Combined information from the neural and muscular structures will allow to understand the exact adaptations of the muscle in response to a given input (neural drive to the muscle). Changes at different levels of the nervous system will affect the control of motor units and mechanical forces during resistance training, thus impacting the potential hypertrophic adaptations. Additionally, this article addresses how neural adaptations and fatigue accumulation that occur when resistance training may influence the hypertrophic response and propose neurophysiological assessments that may improve our understanding of resistance training variables that impact on muscular adaptations.

The Validity of Perceived Recovery Status as a Marker of Daily Recovery Following a High-Volume Back-Squat Protocol

Although a variety of tools to monitor recovery have been developed, many are impractical for daily use due to cost, time, and challenges with interpretation. The Perceived Recovery Status (PRS) scale was recently developed as an expeditious, noninvasive tool to assess recovery status. While PRS has been strongly associated with repeated sprinting performance, a paucity of research exists relating PRS and performance recovery following resistance exercise. Purpose: The purpose of this study was to evaluate the sensitivity of PRS as a subjective marker of recovery up to 72 hours after a high-volume back-squat protocol. Methods: Eleven resistance-trained men reported to the laboratory on 5 separate occasions (1 familiarization session and 4 testing sessions). The first testing session was considered the baseline session and consisted of a nonfatiguing performance assessment (ie, countermovement jumps and back squats) and a fatiguing back-squat protocol of 8 sets of 10 at 70% 1-repetition maximum separated by 2 minutes of recovery. Participants returned 24, 48, and 72 hours following baseline to provide a PRS rating and complete the performance assessment. Results: Repeated-measures correlations revealed strong associations between PRS countermovement jump (r = .84) and mean bar velocity (r = .80) (both P < .001). Conclusions: The current findings suggest that PRS can be used as a method to effectively assess daily recovery following a fatiguing bout of resistance exercise. Practitioners are cautioned that the relationship between PRS and performance recovery is individualized, and equivalent PRS scores between individuals are not indicative of similar recovery.

Detection of Muscle Activation during Resistance Training Using Infrared Thermal Imaging

Infrared thermal imaging has been widely used to show the correlation between thermal characteristics of the body and muscle activation. This study aims to investigate a method using thermal imaging to visualize and differentiate target muscles during resistance training. Thermal images were acquired to monitor three target muscles (i.e., biceps brachii, triceps brachii, and deltoid muscle) in the brachium while varying the training weight, duration, and order of training. The acquired thermal images were segmented and converted to heat maps. By generating difference heat maps from pairs of heat maps during training, the target muscles were clearly visualized, with an average temperature difference of 0.86 °C. It was observed that training order had no significant effect on skin surface temperature. The difference heat maps were also used to train a convolutional neural network (CNN) to show the feasibility of target muscle classification, with an accuracy of 92.3%. This study demonstrated that infrared thermal imaging could be effectively utilized to locate and differentiate target muscle activation during resistance training.

Equating Resistance-Training Volume Between Programs Focused on Muscle Hypertrophy

Calculating resistance-training volume in programs focused on muscle hypertrophy is an attempt to quantify the external workload carried out, then to estimate the dose of stimulus imposed on targeted muscles. The volume is usually expressed in some variables that directly affected the total training work, such as the number of sets, repetitions, and volume-load. These variables are used to try to quantify the training work easily, for the subsequent organization and prescription of training programs. One of the main uses of measures of volume quantification is seen in studies in which the purpose is to compare the effects of different training protocols on muscle growth in a volume-equated format. However, it seems that not all measures of volume are always appropriate for equating training protocols. In the current paper, it is discussed what training volume is and the potentials and shortcomings of each one of the most common ways to equate it between groups depending on the independent variable to be compared (e.g., weekly frequency, intensity of load, and advanced techniques).

An Intense, But Ecologically Valid, Resistance Exercise Session Does Not Alter Growth Factors Associated With Cognitive Health

The purpose of this investigation was to assess the acute changes in growth factors associated with cognitive health following two ecologically valid, intense resistance exercise sessions. Twenty-nine late-middle-aged adults performed one session of either (a) moderate-load resistance exercise or (b) high-load resistance exercise. Venous blood was collected prior to warm-up, immediately following exercise and 30 min following exercise. Serum was analyzed for brain-derived neurotrophic factor, insulin-like growth factor 1, and vascular endothelial growth factor. Session intensity was determined by blood lactate concentration and session rating of perceived exertion. Postexercise blood lactate was greater following moderate-load when compared with high-load resistance exercise. Subjective session intensity was rated higher by the session rating of perceived exertion following moderate-load when compared with high-load resistance exercise. No differences were observed in serum growth factor levels between groups. Ecologically valid and intense moderate-load or high-load exercise methods do not alter serum growth factor levels in late-middle-aged adults.

Sessional work-rate does not affect the magnitude to which simulated hypoxia can augment acute physiological responses during resistance exercise

PURPOSE

To investigate whether performing resistance exercise in hypoxia augments physiological and perceptual responses, and if altering work-rate by performing repetitions to failure compared to sub-maximally increases the magnitude of these responses.

METHODS

Twenty male university students (minimum of 2 year resistance training experience) completed four sessions, two in hypoxia (fraction of inspired oxygen [F_iO₂] = 0.13), and two in normoxia (F_iO₂ = 0.21). For each condition, session one comprised three sets to failure of shoulder press and bench press (high work-rate session), while session two involved the same volume load, distributed over six sets (low work-rate session). Muscle oxygenation (triceps brachii), surface electromyographic activity (anterior deltoid, pectoralis major, and triceps brachii), heart rate (HR), and arterial blood oxygen saturation were recorded. Blood lactate concentration ([Bla^-]) was recorded pre-exercise and 2 min after each exercise. Muscle thickness was measured pre- and post-exercise via ultrasound.

RESULTS

Muscle oxygenation values during sets and inter-set rest periods were lower in hypoxia vs normoxia (p = 0.001). Hypoxia caused greater [Bla^-] during the shoulder press of failure sessions (p = 0.003) and both shoulder press (p = 0.048) and bench press (p = 0.005) of non-failure sessions. Hypoxia increased HR during non-failure sessions (p < 0.001). There was no effect of hypoxia on muscular swelling, surface electromyographic activity, perceived exertion, or number of repetitions performed.

CONCLUSIONS

Hypoxia augmented metabolite accumulation, but had no impact on any other physiological or perceptual response compared to the equivalent exercise in normoxia. Furthermore, the magnitude to which hypoxia increased the measured physiological responses was not influenced by sessional work-rate.

Acute effects of equated volume-load resistance training leading to muscular failure versus non-failure on neuromuscular performance

Background/objective

The aim of this study was to compare the acute effects of resistance training to failure (TF) and non-failure (TNF) with volume-load equalization on neuromuscular performance in recreationally resistance-trained adults.

Methods

Twenty-two trained men (age 21.4 ± 2.3 years) were included in a controlled, randomized, and design cross-over investigation with two experimental conditions and one-week of washout interval between them. The participants performed parallel back-squat adopting TF or TNF with volume, intensity, and rest between sets equalized. Countermovement jump (CMJ) height and peak power (PP) were used as mechanical indicators of neuromuscular performance. The mechanical variables were assessed in five moments (pre-experiment, post 15-s, 10-min, 20-min, and 30-min).

Results

When compared with the TNF condition, TF presented greater decrement on CMJ height (P < 0.001) and PP (P < 0.001) performance. The CMJ height and PP performance in parallel back-squat exercise following the TNF condition returned to the pre-experiment values 10-min after (P > 0.05). On the other hand, the TF condition promoted greater decrement in CMJ and PP performance compared with the pre-experiment and TNF protocol even 20-30 min later (P < 0.05).

Conclusion

These findings suggest that TF promotes greater acute impairment on neuromuscular performance even when volume-load is equalized.

Does rest interval between sets affect resistance training volume, density, and rating of perceived exertion when adopting the crescent pyramid system in young women?

BACKGROUND

The rest interval between sets can affect the responses to resistance training. Thus, the purpose of this study was to compare the effects of different rest intervals (RI) on volume, density, and rating of perceived exertion (RPE) when adopting a crescent pyramid (CP) system.

METHODS

Twenty young women (21.1±2.6 years, 1.59±0.06 m, 58.5±9.3 kg) participated in this study. All participants performed three experimental sessions of the leg press exercise in 5 sets until voluntary muscular failure at 60%, 65%, 70%, 75%, and 80% of one-repetition maximum (1RM). A randomized and crossover design was used so that in each session one of three RI (RI-1 = 1 min, RI-2 = 2 min, and RI-3 = 3 min) was tested.

RESULTS

The participants performed a significantly larger volume in the RI-3 (12820±3134 kg) when compared to RI-1 (10367±3053 kg) condition (P<0.05). The volume did not differ between RI-2 and RI-3 (P>0.05). The density was higher (P<0.05) in RI-1 (43.1±12.7 kg/s) when compared RI-2 (25.6±5.8 kg/s) and RI-3 (17.7±4.3 kg/s). The RI-2 presented higher density compared to RI-3 condition (P<0.05). The RPE was not different between the three conditions (P>0.05).

CONCLUSIONS

The use of 2 minutes of rest between sets allowed the performance of a high volume-load and density of the session in young women. In addition, the three experimental sessions provided a high perception of effort.

The interplay between internal and external load parameters during different strength training sessions in resistance-trained men

External load influences internal load in resistance training (RT). The purpose of the present study was to compare the total volume-load, perceptual and stress responses during three different RT protocols. Twelve resistance-trained men completed three different RT protocols with the back squat and bench press exercises: (1) power (POW) (5 sets of 6 repetitions at 50%1RM, 2-min of rest), (2) hypertrophy (HYP) (5 sets-to-failure at 75%1RM, 2-min of rest), and (3) strength (STR) (5 sets-to-failure at 90%1RM, 3-min of rest). Volume-load (kg × reps.), session rating of perceived exertion (sRPE), training impulse (TRIMP; reps. × sRPE), cortisol, immunoglobulin A (IgA), lactate, and creatine kinase (CK) were assessed before and/or after the sessions. HYP was the most demanding session in terms of volume-load (p < 0.001), TRIMP (p < 0.001), cortisol (p = 0.001), lactate (p < 0.001), and CK (p = 0.001). Despite POW exhibited a greater volume-load than STR (p = 0.016), the latter exhibiting a greater sRPE (p < 0.001), and a greater post-session CK (p = 0.05). However, the TRIMP of STR and POW were not statistically different (152 vs. 260 AU; p = 0.089). These specific responses could be meditated by the presence of muscular failure. When pooling all the sessions, significant correlations were revealed among external and internal stress markers (r = 0.35-0.80; p ≤ 0.05). The use of TRIMP could be recommended as a simple and valid monitoring tool which integrates into a single parameter the internal and the external loads of RT sessions.

Twelve weeks of resistance training does not influence peripheral levels of neurotrophic growth factors or homocysteine in healthy adults: a randomized-controlled trial

INTRODUCTION

There is growing evidence for a preventative effect of resistance training on cognitive decline through physiological mechanisms; yet, the effect of resistance training on resting growth factors and homocysteine levels is incompletely understood. This study aimed to investigate the effect of intense resistance training, for 12 weeks, on changes in peripheral growth factors and homocysteine in late middle-aged adults.

METHODS

45 healthy adults were enrolled into the single-site parallel groups' randomized-controlled trial conducted at the Department of Exercise Science, Strength and Conditioning Laboratory, Murdoch University. Participants were allocated to the following conditions: (1) high-load resistance training (n = 14), or (2) moderate-load resistance training (n = 15) twice per week for 12 weeks; or (3) non-exercising control group (n = 16). Data were collected from September 2016 to December 2017. Fasted blood samples were collected at baseline and within 7 days of trial completion for the analysis of resting serum brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1, vascular endothelial growth factor, and plasma homocysteine levels.

RESULTS

No differences in baseline to post-intervention change in serum growth factors or plasma homocysteine levels were observed between groups. A medium effect was calculated for BDNF change within the high-load condition alone (+ 12.9%, g = 0.54).

CONCLUSIONS

High-load or moderate-load resistance training twice per week for 12 weeks has no effect on peripheral growth factors or homocysteine in healthy late middle-aged adults.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12616000690459.

Resistance training enhances delayed memory in healthy middle-aged and older adults: A randomised controlled trial

OBJECTIVES

High-intensity exercise is a potential therapeutic tool to postpone or prevent the onset of cognitive decline. However, there is a lack of sufficient evidence regarding the longitudinal effects of structured resistance training on cognitive function in healthy adults. The purpose of this study was to investigate the effect of two ecologically valid, intense 12-week resistance training programs on cognitive function in late middle-aged adults.

DESIGN

Single-site parallel randomised controlled trial at the Department of Exercise Science strength and conditioning laboratory. Groups allocated by minimisation randomisation.

METHODS

Forty-five healthy adults (age range=41-69 years) were enrolled and randomised into (A) high-load, long rest resistance training (n=14), or (B) moderate-load, short rest resistance training (n=15) twice per week for 12 weeks, or a non-exercising control (n=16). Follow-up within seven days. Data were collected September 2016-December 2017. Cognitive function assessed using the CogState computerised battery. Assessors were blinded to participant group allocation. Secondary outcomes were maximal muscle strength and body composition.

RESULTS

Forty-four participants were analysed in 2018. Delayed verbal memory performance was improved (p=0.02) in resistance training groups (g=0.67-0.79) when compared to the control group, with no differences between training groups. Likewise, increases in maximal muscle strength were observed (p<0.01) in resistance training groups when compared to the control group, with no differences between training groups. No differences in body composition were observed. There were no adverse events or side-effects of the intervention.

CONCLUSIONS

12 weeks of intense resistance training improves delayed verbal memory irrespective of training design (i.e., high-load vs. moderate-load).

TRIAL REGISTRATION

This study is registered at www.anzctr.org.au ACTRN12616000690459.

Examining work-to-rest ratios to optimize upper body sprint interval training

The objective was to compare the metabolic influence of varying work-to-rest ratios during upper body sprint interval training (SIT). Forty-two recreationally-trained men were randomized into a training group [10 s work - 2 min of rest (10:2) or 4 min of rest (10:4), or 30 s work - 4 min of rest (30:4)] or a control group (CON). Participants underwent six training sessions over two weeks. Assessments consisted of a graded exercise test [maximal oxygen consumption (VO₂peak) and peak power output (PPO)], four constant-work rate trials [critical power, anaerobic working capacity, and electromyographic fatigue threshold], and an upper body Wingate test (mean/peak power and total work). Post-training absolute and relative VO₂peak was greater than pre-training for 30:4 (p = .005 and p = .009, respectively), but lower for CON (p = .001 and p = .006, respectively). Post-training PPO was greater in 30:4 (p < .001). No differences were observed during the constant-work rate trials or Wingate test. Traditional SIT appears to have enhanced VO₂peak in the upper body over a short-term two-week intervention.

Acute alterations in the hematological and hemorheological profile induced by resistance training and possible implication for microvascular functionality

Depending on the exercise variables and training design, resistance exercise can be applied to gain muscle mass, prevent diseases like osteoporosis and sarcopenia or generally increase strength capacity. But the influence on blood flow parameters and possible consequences in health and disease are less understood. To examine the possible impact of resistance exercise of different duration on hemorheology, oxidative stress and microvascular function, participants (n = 6) performed lower-limb resistance exercise of the quadriceps femoris. Loading consisted of 1 (S1), 5 (S5) and 10 (S10) sets, on separated days, at the individual 10 repetition maximum. Blood samples were taken before (Pre) and after (Post0) each set as well after a 25-min recovery period (Post25). Hemograms were measured to analyze hematocrit, white blood cell (WBC) count and red blood cell (RBC) count. RBC deformability and aggregation were measured by ektacytometry and syllectometry to determine hemorheological responses. Plasma and RBC nitrate were measured by chemiluminescence detection to determine nitric oxide production. Formation of N-tyrosine and plasma malondialdehyde to determine oxidative stress and lipid peroxidation were measured by immunostaining and ELISA, respectively. Hematocrit, RBC, WBC count and aggregation increased Post0 in each protocol with subsequently decreased values Post25 below Pre values. High effect size was observed regarding deformability during the different sets. RBC nitrite analysis revealed effect size alterations between the trainings, whereas plasma nitrite was not affected. Effects size was evident in lipid peroxidation, whereas N-tyrosine concentration was not altered. Lower-limb resistance exercise induced acute changes in hematological and hemorheological parameters, whereby intermittent hemodilution and plasma shifts seemed the major contributor. The acute adaptations of RBC function seen during short duration resistance exercise might contribute to beneficial effects on microvascular circulation with a low oxidative stress response.