Exercise Professional Education

11/25/2025

More knee pain, less hip and ankle joint power: The relationship between knee osteoarthritis pain and joint power

“A B S T R A C T

It is unknown how knee osteoarthritis pain affects joint power distribution while cycling. The study purposes were to (1) investigate if seat height, workload and any difference in hip or knee extensor strength affected asymmetry of hip, knee and ankle joint power during cycling; and (2) determine the relationship between knee osteoarthritis pain asymmetry and joint power asymmetry at the hips, knees, ankles and total leg. Asymmetry was the difference between dominant and non-dominant legs. Twenty-six participants (13 female, 13 male) with (n = 21) and without (n = 5) symptomatic knee osteoarthritis participated [age 64.3 (7.3) y, body mass index 27.0 (4.1) kg/m2]. Participants completed six cycling bouts at three seat heights (20◦, 30◦, 40◦ minimum knee flexion angle) and two workloads (40 W, 75 W) on a stationary bike. Self-reported pain was recorded for each knee before the first bout and after each bout. Three-dimensional kinematics and kinetics were collected synchronously with motion capture and instrumented pedals. A greater workload was associated with greater hip power asymmetry (p < 0.01); otherwise, seat height and workload did not affect power asymmetry (p > 0.05). Relationships were found between knee pain asymmetry and hip, ankle and total leg power asymmetry (p < 0.01), but not knee (p > 0.05). The hip, ankle and total leg with the more painful knee produced less power than the opposite side. The more painful knee cannot be assumed to produce less power than the contralateral side. These findings show that, at low workloads, clinicians can adjust seat height to patient preference without affecting joint power production during cycling.”

Currie DJ, Grad D, Webster K, Liu H, Acker S, Knowles N, Maly MR. More knee pain, less hip and ankle joint power: The relationship between knee osteoarthritis pain and joint power. J Biomech. 2025 Nov;192:112937. doi: 10.1016/j.jbiomech.2025.112937. Epub 2025 Sep 1. PMID: 40913928.

11/18/2025

Keep that neck strong!

"a b s t r a c t

Objectives:
Primary prevention of concussions is a priority in contact sports, with growing interest in the role of neck strength in mitigating the risks of concussion. The aim of this study was to determine if neck function was associated with in-season concussions in adolescent rugby union and league athletes, and to establish clinical values to identify players with increased risk of sustaining a concussion.

Design:
Prospective cohort study.

Methods:
Assessment of neck function included isometric strength, endurance and proprioception. In-season concussion injuries were recorded. Preliminary multivariate analysis-of-covariance models were conducted to investigate differences in neck function between players who did and did not sustain an in-season concussion. If significant, receiver operated characteristic curves were used to determine optimal cut-points for each variable to distinguish between concussion groups. Unadjusted odds ratios were estimated from the cross tabulation chi-squared test. Significance was set at p < 0.1.

Results:
A total of 43 players (aged 15–18 years) were assessed during preseason. Eleven players sustained a concussion during the season. Players who sustained a concussion during the season had weaker neck extension strength in kilogrammes (p = 0.043, effect size = 0.74) and when normalised to body weight (p = 0.041, effect size = 0.74). The optimal cut-point for extension strength was 32.1 kg (sensitivity 0.64, specificity 0.75) and 3.71 N/kg (sensitivity 0.64, specificity 0.66). Players with a flexor to extensor strength ratio above 0.74 were 3-times more likely to sustain a concussion (p = 0.09). There were no differences for other neck function variables."

Leung FT, Brown DA, Warner E, Shamim S, Harris S, Hides JA. Neck strength deficit is a risk factor for concussion in high school rugby union and rugby league players. J Sci Med Sport. 2025 May;28(5):370-376. doi: 10.1016/j.jsams.2024.11.016. Epub 2024 Dec 4. PMID: 39672717.

11/11/2025

Associations between range of motion and tissue stiffness in young and older people

“Our lives, and our bodies, are dynamic. The physical state of someone in their twenties is probably vastly different from that of someone in their fifties. Naturally, healthcare should also be oriented differently to different age groups. Older people are more likely to fall and hurt themselves because their joints are less flexible than younger people. To minimize these risks and improve quality of life among elderly individuals, it is important to develop measures that improve physical abilities. However, doing so requires a better understanding of the factors that affect joint flexibility, or range of motion (ROM). In younger individuals, longstanding research suggests that skeletal muscle stiffness is the main characteristic that influences ROM. But muscles naturally reduce in size (in a process called atrophy) with age, and older people tend to have muscles that are less stiff than those of younger people. This suggests that the link between muscle stiffness and ROM is not as strong in elderly people. Then what could be the cause?

To find out, Dr. Kosuke Hirata, Mr. Ryosuke Yamadera, and Prof. Ryota Akagi, a team of researchers from Shibaura Institute of Technology (SIT) in Saitama, Japan, measured ankle ROM in a group of young (~20 years) and old (~70 years) adults. In this new study, they started by asking the participants to rest lie down, and then rotate their ankle until they reported feeling pain; the angle of rotation in which the participants could move without feeling pain was the ROM. Researchers also determined tissue stiffness using a variable called "shear wave speed," which was measured with ultrasound. Stiffness was obtained for several calf muscles, the sciatic nerve (main nerve of the leg), and deep fascia (connective tissue).

The researchers had three major hypotheses. First, they believed that ankle ROM was perhaps correlated with muscle stiffness in young but not old people. Second, ROM would be correlated with nerve and fascia stiffness in both young and old people. Third, the two age groups could have different levels of tissue stiffness. "There have not been many studies that looked at the connection between non-muscle tissue stiffness and ROM, and whether there's an age difference here, so our goal was to provide some clearer answers to these questions," explains Dr. Hirata.

The results of their experiments showed that as muscle stiffness decreased, ROM increased in young participants. However, this correlation was not noted in old participants. Ankle ROM also increased as nerve stiffness decreased, but only in old participants. Fascia stiffness was not correlated with ROM in either age group. Overall, non-muscle tissues, specifically nerves, seemed to contribute more to joint flexibility as individuals age.

Prof. Akagi is optimistic about their findings: "Not every one of our hypotheses was supported--for example, we didn't find an association between fascia stiffness and ROM--the key outcome here is that a difference exists in the underlying factors affecting joint flexibility between young and old people."

These findings open up the floor for several overdue discussions. Existing medical care may be biased towards a younger and healthier population, and current exercises and therapy for improving flexibility focuses on muscles, which will not be as effective for elderly people. This study can spur the development of new flexibility training methods that are specific for older people, focusing on targeting and mobilizing nerve bundles, helping to improve the health of elderly individuals. Based on these findings, in the near future, current training modalities may even be exchanged for more effective ones.
After all, life does not stop in your thirties. Healthcare goals shouldn't either.”

Reference
Title of original paper: Associations between range of motion and tissue stiffness in young and older people Journal: Medicine & Science in Sports & Exercise

11/04/2025

Rate of Force Development as a key physiological indicator of health...

“Explosive strength is the ability to increase force or torque as quickly as possible during a rapid voluntary contraction realised from a low or resting level. Rate of force development (RFD), which is derived from the force- or torque-time curves recorded during explosive voluntary contractions (Aagaard et al. 2002a)—hereafter also referred to as rapid or ballistic actions—is increasingly evaluated to characterise explosive strength of athletes, elderly individuals and patients. This is mainly due to the facts that, as compared to pure maximal voluntary contraction (MVC) strength, RFD seems to be (1) better related to most performances of both sport-specific and functional daily tasks (see, e.g., Maffiuletti et al. 2010; Tillin et al. 2013a), (2) more sensitive to detect acute and chronic changes in neuromuscular function (see, e.g., Angelozzi et al. 2012; Crameri et al. 2007; Jenkins et al. 2014b; Penailillo et al. 2015) and (3) potentially governed by different physiological mechanisms (see, e.g., Andersen and Aagaard 2006; Van Cutsem et al. 1998). The ability to properly quantify and interpret RFD obtained during voluntary isometric contractions is therefore extremely important not only for researchers in the field of human and exercise physiology, but also for practitioners in the fields of physical training and rehabilitation.”

Maffiuletti NA, Aagaard P, Blazevich AJ, Folland J, Tillin N, Duchateau J. Rate of force development: physiological and methodological considerations. Eur J Appl Physiol. 2016 Jun;116(6):1091-116. doi: 10.1007/s00421-016-3346-6. Epub 2016 Mar 3. PMID: 26941023; PMCID: PMC4875063.

10/28/2025

Interesting article: Scapular kinematics and task specificity: The effect of load direction

“Abstract
Our current understanding of healthy scapula motion is mainly based on studying the shoulder when it is generating an abduction torque against gravity. However, the shoulder can perform diverse tasks beyond abduction. In particular, little attention has been given to how scapula motion contributes to concentric adduction despite its involvement in high-demand tasks such as rock climbing and wheelchair transfers. Investigating scapular kinematics during concentrically loaded arm-lowering can provide insight into the mechanical demands underlying healthy scapula motion. In this study, we combined biplanar videoradiography and optical motion capture with a controllable cable machine to compare the three- dimensional humerothoracic, glenohumeral, and scapulothoracic kinematics between a weighted pull-down task (involving concentric shoulder adduction) and a weighted press-up task (involving concentric shoulder abduction) in ten healthy adults. We observed significantly more scapulothoracic upward rotation and less glenohumeral abduction during concentric adduction than concentric abduction. Our findings indicate that scapula upward rotation is not simply a function of overall humerothoracic elevation, but instead varies in a load-specific manner – potentially to orient the glenoid in a way that facilitates glenohumeral joint stability. We also observed substantial inter-individual variability in scapular kinematics within a task, and in how individuals responded to the different tasks. Our findings help provide a more well-rounded understanding of healthy scapular kinematics such that we can better identify and treat unhealthy motion (i.e., dyskinesis). Our findings can also inform musculoskeletal models that simulate scapulothoracic kinematics.”

E.C.S. Lee, N.M. Young, R.L. Lawrence, M.J. Rainbow, Scapular kinematics and task specificity: The effect of load direction, Journal of Biomechanics (2025), doi: https://doi.org/10.1016/j.jbiomech. 2025.112932

10/21/2025

10/20/2025

Greg discussing how emotional responses to injuries change the motor output of an injured region let alone the whole body. Why does an individual move the way they do? Better do your homework! The initial interview combined with a thorough assessment of motor expression combined with how they think and feel about moving and holding positions is key to the interpretation of observations.

Exercise Professional Education - think outside the box!

10/14/2025

Age and recovery

"Old people (> 60 yrs old) respond differently to strength training compared to young people. One feature is their ability to recover from exercise. Animal models have shown that old subjects display more muscle damage in response to a workout of eccentric contractions compared to young subjects. This appears to be caused by their muscle fibers having reduced capacity for lateral force transmission (due to a loss of dystrophin), leading to overstretching of the muscle fibers. Yet, human studies do not always report that old people display more post-workout fatigue than young people. This observation can likely be attributed to their lower levels of motor unit recruitment (indeed, the fast twitch muscle fibers of the highest-threshold motor units are the most vulnerable to damage). Even so, recovery rates post-workout are much slower in elderly people (even when exactly the same amount of fatigue is experienced immediately after exercise). This indicates that the repair and regeneration processes that facilitate recovery from post-workout fatigue are less effective in elderly muscle tissue. In practice, this means that elderly lifters cannot make use of the same volume-frequency combinations as young lifters. Animal models have shown that while young subjects can recover from a given workout volume performed 3 times per week (and thereby make gains in strength and size), old subjects cannot recover from the same training program (and so do not make gains in strength or size). Yet, those same old subjects can make progress by doing the same workout volumes twice per week (or by doing lower workout volumes 3 times per week)."

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10/07/2025

Chronic Plantar Heel Pain is Principally Associated With Waist Girth (Systemic) and Pain (Central) Factors, Not Foot Factors: A Case-Control Study

"Objectives
To determine the independent associations of potential clinical, symptom, physical activity, and psychological factors with chronic plantar heel pain.

Design
Case-control.

Methods
We investigated associations by comparing 220 participants with chronic plantar heel pain (>3 months) and 100 age- and sex-matched controls recruited randomly from the electoral roll. Exposures measured were waist girth, BMI, body composition, clinical measures of foot and leg function, physical activity by accelerometry, depression and pain catastrophising, symptoms of prolonged morning stiffness anywhere in the body, and multisite pain. Data were analysed using multivariable conditional logistic regression.

Results
Waist girth (cm) (OR 1.06; 95% CI 1.03 to 1.09), ankle plantarflexor strength (kg) (OR 0.98; 95% CI 0.97 to 0.99), pain at multiple sites (OR 2.76; 95% CI 1.29 to 5.91 (pain at 1 other site), to OR 10.45; 95% CI 3.66 to 29.81 (pain at 4 or more other sites)) and pain catastrophising status (none, some or catastrophiser) (OR 2.91; 95% CI 1.33 to 6.37 (some), OR 6.79; 95% CI 1.91 to 24.11 (catastrophising)) were independently associated with chronic plantar heel pain. There were univariable but not independent associations with morning stiffness, first metatarsophalangeal joint extension ROM, depression and BMI, and no significant associations with physical activity or body composition by bioimpedance analysis.

Conclusion
Waist girth, ankle plantarflexor strength, multisite pain and pain catastrophising, but not foot-specific factors, were independently associated with chronic plantar heel pain. Three of four of these factors reflect central or systemic associations."

J Orthop Sports Phys Ther, Epub 7 May 2021. doi:10.2519/jospt.2021.10018

09/30/2025

Deep and superficial cervical muscles respond differently to
unstable motor skill tasks

"A B S T R A C T
Biomechanical modelling and physiological studies suggest that various spinal muscle layers differ in their contribution to spine movement and stiffness. This study aimed to investigate the
activation of deep and superficial muscles in stable and unstable task conditions. Nine healthy participants performed a task of controlling a metal ball on a plate fixed to the head in seated
position. In unstable tasks, visual feedback was provided by mirrors to move the ball to the centre of the plate by small head movements and maintain the position for 3 s. Task difficulty was
adjusted in a stepwise progression of difficulty using five surfaces with materials of decreasing resistance. In the stable condition, the ball was fixed to the plate's centre. EMG was recorded with surface (sternocleidomastoid, anterior scalenes, upper trapezius) and fine-wire electrodes (re**us capitis posterior major, obliquus inferior, multifidus, semispinalis cervicis, splenius capitis). The outcome variable was root mean square (RMS) EMG during the part of the task when the ball was
maintained in the centre position. Results revealed greater cervical muscle activity in the unstable than stable conditions (p

09/29/2025

The first ever MSS Full Immersion Experience Course is in the books. Great group of passionate and dedicated professionals paving the way for out of the box problem solving! 🔥

09/27/2025

A great day of problem solving turned into an even better night of company!

An incredible dinner in Columbus, OH with the crew in town for the MSS Full Immersion weekend at the office!