Andrew Vigotsky

Northwestern University | NU · Department of Biomedical Engineering

Surface electromyography (sEMG) is a popular research tool in sport and rehabilitation sciences. Common study designs include the comparison of sEMG amplitudes collected from different muscles as participants perform various exercises and techniques under different loads. Based on such comparisons, researchers attempt to draw conclusions concerning...

Joint stiffness is often measured to make inferences about the stiffness of muscle groups, but little can be gleaned about individual muscles. Decomposing the muscular origins of joint stiffness may inform treatment targets for conditions like spasticity. To complement joint stiffness, shear wave ultrasound elastography has been used to estimate th...

We describe improbable data patterns in the work of Barbalho et al.

Millions of chronic (non-cancer) pain patients manage their pain with long-duration opioid use1-3, but the neurobiological implications of stable long-term opioid consumption remain unknown. Here, we contrasted the clinical profiles and brain structure and function of 70 chronic back pain patients prescribed opioids (CBP+O, average opioid exposure...

Decreasing body mass index (BMI) reduces head motion in resting‐state fMRI (rs‐fMRI) data. Yet, the mechanism by which BMI affects head motion remains poorly understood. Understanding how BMI interacts with respiration to affect head motion can improve head motion reduction strategies. A total of 254 patients with back pain were included in this st...

How does the human brain generate coherent, subjective perceptions—transforming yellow and oblong visual sensory information into the perception of an edible banana? This is a hard problem. According to the standard viewpoint, processing in groups of dedicated regions—identified as active “blobs” when using functional magnetic resonance imaging (fM...

Effort and the perception of effort (PE) have been extensively studied across disciplines, resulting in multiple definitions. These inconsistencies block scientific progress by impeding effective communication between and within fields. Here, we present an integrated perspective of effort and PE that is applicable to both physical and cognitive act...

Background Total knee replacement (TKR) is the gold standard treatment for end‐stage chronic osteoarthritis pain, yet many patients report chronic postoperative pain after TKR. The search for preoperative predictors for chronic postoperative pain following TKR has been studied with inconsistent findings. Methods This study investigates the predict...

Chronic pain is commonly treated with long-term opioids, but the neuropsychological outcomes associated with stable long-duration opioid use remain unclear. Here, we contrasted the psychological profiles, brain activity, and brain structure of 70 chronic back pain patients on opioids (CBP+O, average opioid exposure 6.2 years) with 70 patients manag...

Total knee replacement (TKR) is the gold-standard treatment for end-stage chronic osteoarthritis pain, yet many patients report chronic postoperative pain after TKR. The search for preoperative predictors for chronic postoperative pain following TKR has been studied with inconsistent findings. This study investigates the predictive value of quantit...

Objective Few effective treatments improve upper extremity (UE) function after stroke. Immersive virtual reality (imVR) is a novel and promising strategy for stroke UE recovery. We assessed the extent to which imVR-based UE rehabilitation can augment conventional treatment and explored changes in brain functional connectivity (FC) that were related...

The value of surface electromyograms (EMGs) lies in their potential to non-invasively probe the neuromuscular system. Whether muscle excitation may be accurately inferred from bipolar EMGs depends on how much the detected signal is both sensitive and specific to the excitation of the target muscle. While both are known to be a function of inter-ele...

Introduction It is commonly accepted that traveling across time zones affects sport performance (i.e. via jet lag). This belief is based on poor quality evidence for team sports and simplistic analyses, such as t-tests and linear regression, to explore complex phenomena. For instance, Roy & Forest used such analyses to examine win percentages for t...

We examined how set-volume equated resistance training using either the back squat (SQ) or hip thrust (HT) affected hypertrophy and various strength outcomes. Untrained college-aged participants were randomized into HT (n = 18) or SQ (n = 16) groups. Surface electromyograms (sEMG) from the right gluteus maximus and medius muscles were obtained duri...

Effort and the perception of effort have been extensively studied across multiple disciplines, resulting in disparate definitions across the literature. Inconsistencies in definitions impede scientific progress by blocking effective communication between and within disciplines. Here, we introduce a resource-based framework that comprehensively defi...

Surface EMG (sEMG) has been used to compare loading conditions during exercise. Studies often explore mean/median frequencies. This potentially misses more nuanced electrophysiological differences between exercise tasks. Therefore, wavelet-based analysis was used to evaluate electrophysiological characteristics in the sEMG signal of the quadriceps...

The neural mechanisms for the persistence of pain after a technically successful arthroplasty in osteoarthritis (OA) remain minimally studied, and direct evidence of the brain as a predisposing factor for pain chronicity in this setting has not been investigated. We undertook this study as a first effort to identify presurgical brain and clinical m...

Purpose: We examined how set-volume equated resistance training using either the back squat (SQ) or hip thrust (HT) affected hypertrophy and various strength outcomes. Methods: Untrained college-aged participants were randomized into HT (n=18) or SQ (n=16) groups. Surface electromyograms (sEMG) from the right gluteus maximus and medius muscles were...

Responder analyses are methods for analyzing randomized controlled trials, which purport to identify individuals or subgroups of study participants who experienced a "clinically meaningful" improvement from a treatment. Unfortunately, responder analyses have numerous methodological shortcomings, which preclude inferences concerning individual respo...

Purpose: Collecting reliable and valid rating of perceived effort (RPE) data requires properly anchoring the scales’ upper limits (i.e., the meaning of 10 on a 0–10 scale). Yet, despite their importance, anchoring procedures remain understudied and theoretically underdeveloped. Here we propose a new task-based anchoring procedure that distinguis...

The purpose of this study was to improve our understanding of the relative contributions of biomechanical, anthropometric, and psychological factors in explaining maximal bench press (BP) strength in a heterogeneous, resistance-trained sample. Eighteen college-aged participants reported to the laboratory for three visits. The first visit consisted...

Background and Purpose: Few effective treatments improve upper extremity (UE) function after stroke. Immersive Virtual Reality (imVR) is a novel and promising strategy for stroke UE recovery. However, research on immersive VR-based UE rehabilitation has been minimal. Here we present a randomized controlled trial to assess the effectiveness of imVR-...

Functional magnetic resonance imaging (fMRI) of the human spinal cord (SC) is a unique non-invasive method for characterizing neurovascular responses to stimuli. Group-analysis of SC fMRI data involves co-registration of subject-level data to standard space, which requires manual masking of the cord and may result in bias of group-level SC fMRI res...

We used a recently advanced technique, morphometric similarity (MS), in a large sample of lumbar disc herniation patients with chronic pain (LDH-CP) to examine morphometric features derived from multimodal MRI data. To do so, we evenly allocated 136 LDH-CPs to exploratory and validation groups with matched healthy controls (HC), randomly chosen fro...

Background: Progressive overload is a principle of resistance training exercise program design that typically relies on increasing load to increase neuromuscular demand to facilitate further adaptations. However, little attention has been given to another way of increasing demand-increasing the number of repetitions. Objective: This study aimed...

We studied the behavioral consequences of fentanyl vapor self-administration (SA) in mice with and without chronic neuropathic pain (one month after spared-nerve injury(SNI) model or sham injury). We assessed fentanyl consumption, motivation, and seeking during as well as anxiety, hyperactivity, immobility, and pain for two regimens of fentanyl SA:...

How does the human brain generate coherent, subjective perceptions—transforming yellow and oblong visual sensory information into the perception of an edible banana? This is a hard problem. The standard viewpoint posits that anatomical and functional networks integrate local, specialized processing across the brain to somehow construct unique perce...

This study examines cognitive, emotional, sensory, and motor function in patients with chronic back pain (CBP) with and without long-term opioid exposure (CBP+O vs. CBP−O) and the influence of race and sex on these outcomes. We recruited 64 CBP+O (mean 7.4 years of opioid use) and 64 matched CBP−O. We collected pain intensity, pain duration, NIH To...

The purpose of this study was to evaluate differences in changes in muscle strength and muscle thickness (MT) of the plantar flexor muscles between traditional resistance training (RT) involving passive rest and RT combined with inter-set stretch in the calf raise exercise. Employing a within-subject design, 21 young, healthy men performed plantar...

Previous research reports suggest greater baseline variability is associated with greater pain relief in those who receive a placebo. However, studies that evidence this association do not control for confounding effects from regression to the mean and natural history. In this report, we analyzed data from two randomized clinical trials (Placebo I...

Functional magnetic resonance imaging (fMRI) of the human spinal cord (SC) is an emerging method for understanding neurovascular responses to stimuli. Group-analysis of SC fMRI data involves co-registration of subject-level data to standard space, which requires manual masking of the cord and may result in bias of group-level SC fMRI results. To te...

Surface electromyography amplitudes are commonly measured in acute sports and exercise science studies to make inferences about muscular strength, performance, and hypertrophic adaptations that may result from different exercises or exercise-related variables. Here, we discuss the presumptive logic and assumptions underlying these inferences, focus...

A growing number of studies claim to decode mental states using multi-voxel decoders of brain activity. It has been proposed that the fixed, fine-grained, multi-voxel patterns in these decoders are necessary for discriminating between and identifying mental states. Here, we present evidence that the efficacy of these decoders might be overstated. A...

Towards the goal of obtaining non-invasive biomarkers reflecting the anterior cruciate ligament’s (ACL) loading capacity, this project aimed to develop a magnetic resonance imaging (MRI)-based method facilitating the measurement of ACL elongations during the execution of knee stress tests. An MRI-compatible, computer-controlled, and pneumatically d...

Pain relief, or a decrease in self-reported pain intensity, is frequently the primary outcome of pain clinical trials. Investigators commonly report pain relief in one of two ways: using raw units (additive) or using percentage units (multiplicative). However, additive and multiplicative scales have different assumptions and are incompatible with o...

Hypertrophy can be operationally defined as an increase in the axial cross-sectional area of a muscle fiber or whole muscle, and is due to increases in the size of pre-existing muscle fibers. Hypertrophy is a desired outcome in many sports. For some athletes, muscular bulk and, conceivably, the accompanying increase in strength/power, are desirable...

IntroductionThe opiate epidemic has severe medical and social consequences. Opioids are commonly prescribed in patients with chronic pain, and are a main contributor to the opiate epidemic. The adverse effects of long-term opioid usage have been studied primarily in dependence/addiction disorders, but not in chronic pain. Here, we examine the added...

The size principle is a theory of motor unit (MU) recruitment that suggests MUs are recruited in an orderly manner from the smallest (lower threshold) to the largest (higher threshold) MUs. A consequence of this biophysical theory is that, for isometric contractions, recruitment is dependent on the intensity of actual effort required to meet task d...

Aim The aim of this study was to examine the associations between the injury risk and the acute (AL) to chronic (CL) workload ratio (ACWR) by substituting the original CL with contrived values to assess the role of CL (i.e., the presence and implications of statistical artefacts). Methods Using previously published data, we generated a contrived A...

Objectives Lower body power declines with age and is associated with decreased physical function in older adults. However, the majority of the tools available to measure power are expensive and require considerable space and expertise to operate. The purpose of this study was to assess the validity, reliability, and measurement error of a sit-to-st...

High-profile studies claim to assess mental states across individuals using multi-voxel decoders of brain activity. The fixed, fine-grained, multi-voxel patterns in these "optimized" decoders are purportedly necessary for discriminating between, and accurately identifying, mental states. Here, we present compelling evidence that the efficacy of the...

Recent discussions in the sport and exercise science community have focused on the appropriate use and reporting of effect sizes. Sport and exercise scientists often analyze repeated-measures data, from which mean differences are reported. To aid the interpretation of these data, standardized mean differences (SMD) are commonly reported as a descri...

Head motion is a major confounding factor impairing the quality of functional magnetic resonance imaging (fMRI) data. In particular, head motion can reduce analytical efficiency, and its effects are still present even after preprocessing. To examine the validity of motion removal and to evaluate the remaining effects of motion on the quality of the...

Recent discussions in the sport and exercise science community have focused on the appropriate use andreporting of effect sizes. Sport and exercise scientists often analyze repeated-measures data, from whichmean differences are reported. To aid the interpretation of these data, standardized mean differences(SMD) are commonly reported as description...

The interaction between osteoarthritis (OA) pain and brain properties remains minimally understood, although anatomical and functional neuroimaging studies suggest that OA, similar to other chronic pain conditions, may impact as well as partly be determined by brain properties. Here, we studied brain grey matter (GM) properties in OA patients sched...

It has been proposed that superior muscle hypertrophy may be obtained by training muscles predominant in type I fibers with lighter loads and those predominant in type II fibers with heavier loads. Purpose: To evaluate longitudinal changes in muscle strength and hypertrophy of the soleus (a predominantly slow-twitch muscle) and gastrocnemius (muscl...

Importance Opioid prescriptions for treatment of pain in emergency departments (EDs) are associated with long-term opioid use. The temporal pattern of opioid prescribing in the context of the opioid epidemic remains unknown. Objective To examine the temporal pattern of opioid prescribing within an ED for varying pain conditions between 2009 and 20...

Aim: The aim of this study is to assess the presence and implications of statistical artefacts created by a commonly used indicator of injury risk in both research and practice: the ratio between acute workload (AL) and chronic workload (CL), named ACWR. Methods: Using previously published data, we generated a contrived ACWR by dividing the AL by f...

The primary means of disseminating sport and exercise science research is currently through journal articles. However, not all studies, especially those with null findings, make it to formal publication. This publication bias towards positive findings may contribute to questionable research practices. Preregistration is a solution to prevent the pu...

We aimed to investigate the effects of resistance training (RT) combined with no-load isometric actions (iso-holds) during the inter-set recovery period versus RT that involves passive inter-set rest on muscular strength, muscular hypertrophy, and muscular endurance in resistance-trained men. Twenty-seven resistance-trained male volunteers were ran...

Dankel & Loenneke (2019) recently presented a new approach to identifying subgroups in parallel group study designs. Here, we briefly discuss our statistical concerns with proposed approach. We reveal that the error rates of the Danke-Loenneke approach are much higher than the claimed 5%, and that these error rates are dependent on numerous factors...

Biomechanics principally stems from two disciplines, mechanics and biology. However, both the application and language of the mechanical constructs are not always adhered to when applied to biological systems, which can lead to errors and misunderstandings within the scientific literature. Here we address three topics that seem to be common points...

Skeletal muscle is highly adaptable and has consistently been shown to morphologically respond to exercise training. Skeletal muscle growth during periods of resistance training has traditionally been referred to as skeletal muscle hypertrophy, and this manifests as increases in muscle mass, muscle thickness, muscle area, muscle volume, and muscle...

The primary means for disseminating sport and exercise science research is currently through journal articles. However, not all studies, especially those with null findings, make it to formal publication. This publication bias towards positive findings may contribute to questionable research practices. Preregistration is a solution to prevent the pub...

Different stance widths are commonly utilized when completing the barbell back squat during athletic general preparedness training. Width manipulation is thought to influence sagittal plane stimuli to the hip and knee extensors, the primary extensor musculature in the squat. However, how width manipulation affects frontal plane stimuli is less unde...

Abstract Iacono, AD, Vigotsky, AD, Laver, L, and Halperin, I. Beneficial effects of small-sided games as a conclusive part of warm-up routines in young elite handball players. J Strength Cond Res XX(X): 000–000, 2019—The aim of this study was to compare the effects of small-sided games (SSGs) and traditional warm-up strategies on the mechanical, ph...

Heavy barbell back squatting is commonly seen as an essential general preparedness exercise for the hip and knee extensors[1]. Posited as a functional exercise, it encompasses similar kinematics to many athletic movements, including acceleration and change of direction. Moreover, anecdotes argue that a narrower squat stance is more transferable to...

Shear-wave (SW) ultrasound elastography is both a clinical and research tool that is increasingly being used to quantify the material properties of muscle. However, how SW velocity relates to stiffness changes on the joint- and musclelevels is poorly understood. Therefore, the purpose of this work was to develop a biomechanical model to estimate pl...