Per Aagaard

• PhD MSc
• Professor at University of Southern Denmark

Reduced quality of life in patients with myositis is partly due to impairments in muscle strength, muscle endurance and functional capacity. In a recent randomised controlled trial (RCT) (NCT04486261) we showed that high-intensity resistance training improved quality of life, muscle strength, and endurance. This follow-up study aimed to investigate...

Disuse induces a disproportionate loss of muscle force compared with muscle mass, with unclear effects on voluntary muscle activation (VA) and peripheral contractility. Furthermore, the effect of neuromuscular electrical stimulation (NMES) as a disuse countermeasure remains uncertain. We investigated the effects of NMES during bed rest on neuromech...

The purpose of this study was to provide data‐driven recommendations for assessing early‐phase rate of torque development (RTD) in isometric knee extension and flexion, focusing on the optimal number of repetitions performed and trial selection criteria to ensure robust intersession reliability. Twenty subjects (10 males, 10 females) completed two...

Reliable and sensitive testing of physical function is crucial for assessing the effects of treatment or exercise intervention in various patient populations. The present study investigated the test–retest reliability and sensitivity (smallest detectable difference: SDD) of selected physical performance tests commonly used in clinical rehabilitatio...

Background/Objectives: Team handball involves a high number of rapid and forceful muscle actions. Progressive heavy-load resistance training is known to enhance mechanical muscle function; however, its transfer into functional performance in team handball athletes remains largely unknown. The current study aimed to analyze the effects of eight week...

OBJECTIVE: Knee pain is highly prevalent and disabling among the general and working population. This systematic review explored the effectiveness of workplace-based interventions on knee pain among workers. METHODS: A PICO-guided systematic search was performed in PubMed and Web of Science Core Collection for articles published from 2003 until Jan...

Panoramic ultrasound (US) is an extended field‐of‐view (EFOV) imaging technique that enables visualization of large‐scale skeletal muscles. This technique has previously been found to produce valid and reliable quantifications of muscle morphology in primarily young male subjects. The purpose was to investigate the intra‐rater between‐session test–...

Background: Muscle strength asymmetry and athlete introspective measures are associated with musculoskeletal (MSK) sport injury and reinjury. However, the interrelationship between mechanical and subjective measures of concentric and eccentric limb function needs further exploration. This includes investigating if an athlete’s perception of their o...

Myositis is associated with reduced quality of life, which is accompanied by significant impairments in muscle endurance and strength, altogether representing cardinal traits in patients with myositis. This randomised controlled trial aimed to investigate the effect of high-intensity resistance training on quality of life in patients with myositis....

The consequences of short‐term disuse are well known, but effective countermeasures remain elusive. This study investigated the effects of neuromuscular electrical stimulation (NMES) during 5 days of bed rest on retaining lower limb muscle mass and muscle function in healthy young and old participants. One leg received NMES of the quadriceps muscle...

Background Reduced muscle endurance and strength are cardinal traits in patients with myositis[1]. These traits are associated with reduced quality of life[2], thus an increase in endurance and strength could potentially lead to improved quality of life. Our randomised controlled trial (RCT) (NCT04486261) investigated the effects of 16 weeks of pro...

Purpose This study aimed to assess the reliability of lower limb muscle function (knee extensor/flexor peak torque, rate of torque development (RTD), impulse, and countermovement jump (CMJ) performance) and sprint performance (acceleration capacity). Methods CMJ performance was evaluated on a force plate. MVIC, RTD and impulse variables were inves...

Sporadic inclusion body myositis (sIBM) is a subgroup of idiopathic inflammatory myopathies characterised by progressive muscle weakness and skeletal muscle inflammation. Quantitative data on the myofibre morphology in sIBM remains scarce. Further, no previous study has examined fibre type association of satellite cells (SC), myonuclei number, macr...

Background The aim of this study was to examine the test−retest reliability in lower limb muscle strength and rate of torque development (RTD) using isokinetic dynamometry in adults with obesity, with a body mass index (BMI) ≥ 35 kg/m2. Method Thirty-two adults with a BMI of 43.8 ± 6.6 kg/m2 eligible for bariatric surgery were enroled in the study...

Objective To investigate the potential associations between functional capacity, muscle strength, body composition, and disease‐related measures and quality of life in patients with myositis. Methods Baseline measures of functional capacity (functional index 3 (FI3), 2‐minute walk test (2MWT), timed up and go (TUG) and 30‐s sit‐to‐stand (30‐STS)),...

Introduction Osteoarthritis (OA) is a common disease with high socioeconomical costs. In Denmark, standard rehabilitation (SR) consists of a combination of patient education and supervised physical exercise involving a standardized neuromuscular training program. As an evidence-based alternative, high–load (>70% 1RM) resistance training (HIRT) has...

Introduction Heavy‐load free‐flow resistance exercise (HL‐FFRE) is a widely used training modality. Recently, low‐load blood‐flow restricted resistance exercise (LL‐BFRRE) has gained attention in both athletic and clinical settings as an alternative when conventional HL‐FFRE is contraindicated or not tolerated. LL‐BFRRE has been shown to result in...

Despite the frequent occurrence of congested game fixtures in elite ice hockey, the postgame recovery pattern has not previously been investigated. The purpose of the present study was therefore to evaluate the acute decrements and subsequent recovery of skeletal muscle glycogen levels, muscle function and repeated‐sprint ability following ice hock...

Background and objective: No information exists on the long-lasting effects of supraphysiological anabolic androgenic steroids (AAS) usage on the myocellular properties of human skeletal muscle in previous AAS users. We hypothesized former AAS users would demonstrate smaller myonuclei domains (i.e., higher myonuclei density) compared to matched co...

Background Idiopathic inflammatory myopathies – or briefly myositis – has cardinal traits of muscle weakness [1] and decreased muscle endurance [2] in addition to reduced quality of life (QoL) [3] . However, QoL is complex, and it is unclear which factors affect QoL in patients with myositis. Knowledge of these factors and potential associations to...

It has recently been established that myosin, the molecular motor protein, is able to exist in two conformations in relaxed skeletal muscle. These conformations are known as the super-relaxed (SRX) and disordered-relaxed (DRX) states and are finely balanced to optimize ATP consumption and skeletal muscle metabolism. Indeed, SRX myosins are thought...

Introduction: Bariatric surgery is effective at ensuring long-term weight loss in adults with obesity. However, an adverse effect of bariatric surgery is severe muscle wasting (1). Within 3 months following surgery, a loss of ~10% lean body mass (LBM) and ~10% appendicular lean mass (ALM) may be observed (1). One year following surgery, loss of LBM...

Mitochondria are the cellular organelles responsible for resynthesising the majority of ATP. In skeletal muscle, there is an increased ATP turnover during resistance exercise to sustain the energetic demands of muscle contraction. Despite this, little is known regarding the mitochondrial characteristics of chronically strength‐trained individuals a...

Objectives: This study investigated the effect of lower limb immobilization and retraining on postural control and muscle power in healthy old and young men. Methods: Twenty men, nine old (OM:67.3±4.4 years) and eleven young (YM:24.4±1.6 years) underwent 2 weeks of unilateral whole-leg casting, followed by 4 weeks of retraining. Measures include...

OBJECTIVE: To investigate the effect of progressive resistance exercise compared with low-intensity home-based exercises on knee-muscle strength and joint function in people with anterior cruciate ligament (ACL) reconstruction and persistent hamstring strength deficits at 12–24 months after surgery. DESIGN: Randomized controlled superiority trial w...

It has recently been established that myosin, the molecular motor protein, is able to exist in two conformations in relaxed skeletal muscle. These conformations are known as super-relaxed (SRX) and disordered-relaxed (DRX) states and are finely balanced to optimize skeletal muscle metabo-lism. Indeed, SRX myosins are thought to have a 10-fold reduc...

Background Sporadic inclusion body myositis (sIBM) is an acquired disease within the idiopathic inflammatory myopathy (IIM) spectrum, characterized clinically by progressive muscle atrophy, weakness and often severely impaired physical function leading to Sarcopenia. Despite of this, muscle mass and physical function is not routinely assessed in pa...

Previous evidence suggests that resistance training in combination with specific collagen peptides (CP) improves adaptive responses of the muscular apparatus. Although beneficial effects have been repeatedly demonstrated, the underlying mechanisms are not well understood. Therefore, the primary objective of the present randomized trial was to eluci...

Sporadic inclusion body myositis (sIBM) is characterised by skeletal muscle inflammation, progressive muscle loss and weakness, which is largely refractory to immunosuppressive treatment. Low-load blood-flow restricted (BFR) training has been shown to evoke gains in myofibre cross sectional area (mCSA) in healthy adults. This could partially be due...

A retrospective analysis of routine countermovement jump (CMJ) testing, a coupled eccentric-concentric (stretch-shorten-cycle: SSC) movement, was performed in female elite alpine skiers with anterior cruciate ligament (ACL) reconstruction (ACLR) and without ACLR. A total of 567 tests obtained from the daily training environment were analyzed in 41...

Background: Ankle sprain is the most common type of sports injury, especially in team sports. Standing and dynamic landing balance, as an indicator of ankle instability, were investigated using varying experimental approaches. Methods: In the present cross-sectional study, 81 adolescent female elite handball and football players were divided int...

Sporadic inclusion body myositis (sIBM) is an idiopathic inflammatory muscle disease associated with skeletal muscle inflammation and a parallel progressive decline in muscle strength and physical function. Eventually, most sIBM patients require use of wheelchair after about 10 years of diagnosis and assistance to perform activities of daily living...

Background: Although growth differentiation factor 15 (GDF15) is known to increase with disease and is associated with low physical performance, the role of GDF15 in normal ageing is still not fully understood. Specifically, the influence of circulating GDF15 on impairments in maximal muscle power (a major contributor to functional limitations) an...

# Background Reduced activation of the hamstring muscles and specifically the medial semitendinosus muscle (ST) has been shown to be a risk factor for non-contact anterior cruciate ligament (ACL) injury. Specific hamstring strength exercises may show high ST activity, however the effect of unilateral vs. bilateral exercise execution on ST activati...

Background The 30-s sit-to-stand (STS) muscle power test is a valid test to assess muscle power in older people; however, whether it may be used to assess trajectories of lower-limb muscle power through the adult lifespan is not known. This study evaluated the pattern and time course of variations in relative, allometric and specific STS muscle pow...

Introduction Idiopathic inflammatory myopathies (IIMs) are rare diseases characterised by non-suppurative inflammation of skeletal muscles and muscle weakness. Additionally, IIM is associated with a reduced quality of life. Strength training is known to promote muscle hypertrophy and increase muscle strength and physical performance in healthy youn...

Purpose To identify modifiable biomechanical and neuromuscular anterior cruciate ligament (ACL) injury risk factors for first-time ACL injury in adolescent female elite football and team handball players. Methods Adolescent female elite football and handball players with no previous ACL injury participated in the present study. At baseline, player...

Aim: MRI can provide fundamental tools in decoding physiological stressors stimulated by training paradigms. Acute physiological changes induced by three diverse exercise protocols known to elicit similar levels of muscle hypertrophy were evaluated using muscle functional magnetic resonance imaging (mfMRI). Methods: The study was a cross-over st...

Purpose: Increasing age, high quadriceps strength, and low hamstring muscle strength are associated with hamstring strain injury in soccer. The authors investigated the age-related variation in maximal hamstring and quadriceps strength in male elite soccer players from under-13 (U-13) to the senior level. Methods: A total of 125 elite soccer pla...

Prolonged physical inactivity in young adults may lead to deficiencies in musculoskeletal fitness, and thus a need exists to develop physical activity and exercise programmes that are effective of increasing musculoskeletal fitness. The aim of this study, therefore, was to investigate the effects of small-sided team handball training on lower limb...

Background Anterior cruciate ligament (ACL) rupture is a serious injury with a high prevalence worldwide, and subsequent ACL reconstructions (ACLR) appear to be most commonly performed using hamstring-derived (semitendinosus tendon) autografts. Recovery of maximal muscle strength to ≥90% of the healthy contralateral limb is considered an important...

This study aimed to assess the validity and functional relevance of a standardized procedure to assess lower limb muscle power by means of the 30-s sit-to-stand (STS) test when compared to leg extension power (LEP), traditional STS performance and handgrip strength. A total of 628 community-dwelling older subjects (60–93 years) from the Copenhagen...

Aim: Glycogen particles are found in different subcellular localizations, which are utilized heterogeneously in different fibre types during endurance exercise. Although resistance exercise typically involves only a moderate use of mixed muscle glycogen, the hypothesis of the present study was that high-volume heavy-load resistance exercise would...

Study design Comprehensive review and meta‐analysis. Background The recovery in rapid force production measured as the rate of force development (RFD) is not clear after anterior cruciate ligament reconstruction (ACLR). Objectives To evaluate (1) time‐course change of between‐limb asymmetries in isometric knee extension/flexion RFD in individuals...

Aim: Previous reports suggest that low-load muscle exercise performed under blood flow restriction (BFR) may lead to endurance adaptations. However, only few and conflicting results exist on the magnitude and timing of microvascular adaptations, overall indicating a lack of angiogenesis with BFR training. The present study, therefore, aimed to exam...

Aim: To investigate if short-term block-structured training consisting of alternating weeks of blood-flow restricted low-load resistance training (BFR-RT) and conventional free-flow heavy-load resistance training (HL-RT) leads to superior gains in mechanical muscle function, myofiber size and satellite cell (SC) content and myonuclear number compa...

Heavy controlled loads of tendon with prolonged time under tension remains the treatment‐of‐choice in tendinopathy rehabilitation. The use of low‐load resistance exercise (LL, 20‐40% 1RM) in combination with blood flow restriction (BFR) has been advocated as a clinically important rehabilitation tool for persons not tolerating high muscle‐tendon lo...

Introduction: Heavy-load strength training (HLT) is generally considered the Gold Standard exercise modality for inducing gains in skeletal muscle strength. However, use of heavy external exercise loads may be contraindicative in frail individuals. Low-load resistance exercise combined with partial blood-flow restriction (LL-BFR exercise) may offe...

Background Our main goal was to evaluate the pattern and time course of changes in relative muscle power and its constituting components throughout the lifespan. Methods A total of 1305 subjects (729 women and 576 men; aged 20-93 years) participating in the Copenhagen Sarcopenia Study took part. Body mass index (BMI), leg lean mass assessed by DXA...

Background: Sporadic inclusion body myositis (sIBM) is clinically characterised by progressive proximal and distal muscle weakness and impaired physical function while skeletal muscle tissue displays abnormal cellular infiltration of T cells, macrophages, and dendritic cells. Only limited knowledge exists about the effects of low-load blood flow r...

Introduction: A significant step towards sport-related injury prevention is the introduction of easily accessible smartphone applications (apps). However, it is unknown whether this type of app-based instruction facilitates similar acute neuromuscular and biomechanical characteristics of the preventive exercises as achieved when instructed on-site...

Purpose: Numerous daily tasks such as walking and rising from a chair involve bilateral lower limb movements. During such tasks lower extremity function (LEF) may be compromised among older adults. LEF may be further impaired due to high degrees of between-limb asymmetry. The present study investigated the prevalence of between-limb asymmetry in m...

Background: Despite no international consensus on the diagnostic criteria for sarcopenia, low lean mass, muscle strength, and physical function are important risk factors for disability, frailty, and mortality in older individuals, as well as in a wide range of patients with muscle loss. Here, we provide a population-based reference material of to...

Purpose:: This cross-sectional study aimed to investigate the association between hamstring muscle peak torque and rapid force capacity (rate of torque development: RTD) versus sprint performance in elite youth football players. Methods:: Thirty elite academy youth football players (16.75 ± 1.1 years, 176.9 ± 6.7 cm, 67.1 ± 6.9 kg) were included...

Pareja-Blanco, F, Rodríguez-Rosell, D, Aagaard, P, Sánchez-Medina, L, Ribas-Serna, J, Mora-Custodio, R, Otero-Esquina, C, Yáñez-García, JM, and González-Badillo, JJ. Time course of recovery from resistance exercise with different set configurations. J Strength Cond Res XX(X): 000-000, 2018-This study analyzed the response to 10 resistance exercise...

The strategy of the nervous system to activate agonist muscle(s) appears to differ substantially between eccentric versus isometric and concentric contractions1,2,3. Previous study reports have indicated that in untrained individuals the muscle is not fully activated during eccentric contraction despite a maximal volitional effort (MVC). More speci...

Neuromuscular activity is suppressed during maximal eccentric (ECC) muscle contraction in untrained subjects owing to attenuated levels of central activation and reduced spinal motor neuron (MN) excitability indicated by reduced electromyography signal amplitude, diminished evoked H-reflex responses, increased autogenic MN inhibition, and decreased...

Objectives: To investigate the effect of 12 weeks of low-load blood-flow restricted resistance (BFR) training on self-reported and objective physical function, and maximal muscle strength in patients with sporadic inclusion body myositis (sIBM). Method: Twenty-two patients with sIBM were randomized into a training group (BFR group) or a non-exercis...

Young, adolescent female athletes are at particular high risk of sustaining a non-contact anterior cruciate ligament (ACL) injury during sport. Through the last decades much attention has been directed toward various anatomical and biomechanical risk factors for non-contact ACL injury, and important information have been retrieved about the influen...

Background: Reduced lower extremity muscle strength as well as reduced lower extremity muscle pre-activity (defined as muscular activity just prior to initial ground contact) during high-risk movements are factors related to increased risk of non-contact ACL injury in adolescent female athletes. A strong relationship exists between muscle strength...

While short-term disuse negatively affects mechanical muscle function (e.g. isometric muscle strength) little is known of the relative contribution of adaptions in central neural drive and peripheral muscle contractility. The present study investigated the relative contribution of adaptations in central neural drive and peripheral muscle contractil...

Background: Anterior cruciate ligament (ACL) reconstruction, using hamstring auto-graft is a common surgical procedure, which often leads to persistent hamstring muscle-strength deficiency and reduced function. The purpose of this randomized controlled trial (RCT) is to investigate the effect of a combined, progressive, strength and neuromuscular...

The review describes the fitness and health effects of recreational football in women aged 18–65 years. The review documents that 2 × 1 h of recreational football training for 12–16 weeks causes marked improvements in maximal oxygen uptake (5–15%) and myocardial function in women. Moreover, mean arterial blood pressure was shown to decrease by 2–5...

Objective The preseason Nordic Hamstring Protocol (NHP) reduces hamstring strain injuries in football players. Despite persisting injury rates, elite clubs are reluctant to apply the NHP often over concerns of negative impacts on performance. This pilot study investigated if sprint or jump-performance outcomes tended to increase or decrease followi...

This assessor-blinded, randomized controlled superiority trial investigated the efficacy of the 10-week Nordic Hamstring exercise (NHE) protocol on sprint performance in football players. Thirty-five amateur male players (age: 17–26 years) were randomized to a do-as-usual control group (CG; n = 17) or to 10-weeks of supervised strength training usi...

Rate of force development (RFD) refers to the ability of the neuromuscular system to increase contractile force from a low or resting level when muscle activation is performed as quickly as possible, and it is considered an important muscle strength parameter, especially for athletes in sports requiring high-speed actions. The assessment of RFD has...

Background Anterior cruciate ligament (ACL) tear is the most frequent injury in alpine ski racing, and there is a high prevalence of ACL reinjury. Limited data exist on the concurrent pathology with primary ACL tears in elite alpine ski racers and the magnitude of injury progression after primary ACL reconstruction (ACLR). Purpose To evaluate (1)...

Objectives The present study aimed to explore the effect of resistance training in patients with amyotrophic lateral sclerosis (ALS), a disease characterized by progressive motor neuron loss and muscle weakness. Materials and Methods Following a 12-week “lead-in” control period, a population of ALS patients from Funen, Denmark, completed a 12-week...

Key points Muscular contractions performed using a combination of low external loads and partial restriction of limb blood flow appear to induce substantial gains in muscle strength and muscle mass. This exercise regime may initially induce muscular stress and damage; however, the effects of a period of blood flow restricted training on these param...

The purpose of the present review was to: 1) provide an overview of the current understanding on the epidemiology, etiology, risk factors, and prevention methods for anterior cruciate ligament (ACL) injury in alpine ski racing; and 2) provide an overview of what is known pertaining to ACL reinjury and return to sport after ACL injury in alpine ski...

The purpose of this study was to determine the adaptive response of ratings of perceived exertion (RPE) and pain over six consecutive training sessions. Thirty subjects were assigned to either a blood flow restricted training group (BFRT) or a high intensity group (HIT). BFRT group performed four sets (30+15+15+15, respectively) of unilateral leg e...

Introduction: Self-reported physical function, functional capacity, and isolated muscle function were investigated in sporadic inclusion body myositis (sIBM) patients. Methods: SF-36 health survey and 2-min Walk test (2MWT), Timed Up & Go test (TUG), and 30-sec Chair Stand performance were evaluated. Additionally, patients were tested for knee e...

Purpose: The aim of the present study was to investigate the effect and time course of high-frequent low-load resistance training with blood-flow restriction (BFR) on rapid force capacity (i.e. rate of torque development (RTD)). Methods: Ten male subjects (22.8±2.3 years) performed four sets of knee extensor exercise (20%1RM) to concentric failu...