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The Assessment, Management and Prevention of Calf Muscle Strain Open Access Injuries: A Qualitative Study of the Practices and Perspectives of 20 Expert Sports Clinicians

Green, B., McClelland, J.A., Semciw, A.I., Schache, A.G., McCall, A. and Pizzari, T., 2022. The Assessment, Management and Prevention of Calf Muscle Strain Injuries: A Qualitative Study of the Practices and Perspectives of 20 Expert Sports Clinicians. Sports medicine-open, 8(1), pp.1-28.

In today’s letter

• Overview of how to prevent a calf strain from happening

• Professional takeaway =

  (1) Calf strain are multi factorial and thus sport specific demands should be considered when planning “gym” workouts.

  (2) Use Calf endurance test (+30 reps & <10% Limb symmetry) and strength 1.5x body weight do understand the athletes/patients muscular capacity. This helps to highlight areas to target.

  (3) Adjust exercise selection if an increased risk was detected, avoiding activities that could worsen the situation, especially ballistic exercises and heavy calf strengthening.

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Aim of study

The aim of this study was to evaluate the current practices and perspectives of a select group of international experts regarding the assessment, management and prevention of calf muscle strains using in-depth semi-structured interviews

Background info

*Same as previous 2 newsletters*

• The burden of calf muscle strain can result in significant >3 months time-loss, as reported in cases of American football, football, and Australian Football.

• Athletes face an increased susceptibility to recurrent calf muscle strains and other subsequent lower limb injuries, including hamstring strain, compounding the impact of the calf strain

• Despite it being a prevalent issue in various sports, there is a lack of research guiding clinicians on best practices for assessment, management, and prevention.

• In the absence of research on calf muscle strain diagnosis and management, sports medicine practitioners have relied on commentaries and book chapters, which represent a low level of evidence, to inform their clinical decision-making.

• Qualitative research, conducted rigorously to minimise bias, is a powerful tool to inform practice and future research. In-depth interviews in qualitative analyses allow exploration and evaluation of complex areas.

 Methods

• Participants were identified purposefully using publicly available information, the networks of the investigators and identified experts, as well as a review of key research in the field

• Using a consensus approach among investigators, potential participants were sourced from different countries, sports and areas of specialisation to ensure diversity in the sample and to minimise the risk of bias

• As a mini- mum they had:

  (1) postgraduate qualifications in≥1 relevant discipline

  (2) > 5 years of clinical experience in elite sport and/or consulting elite athletes

Interview design

• In-depth interviews were selected as the method to delve into the practices and perspectives of experts involved in the assessment, management, and prevention of calf muscle strain

• The in-depth semi-structured design was employed to facilitate a thorough exploration of participant responses, allowing the recognition of emerging trends and themes.

• The interview guide, provided to participants in advance for approval, served as a framework during the interviews. This approach ensured that data collection covered all relevant topics from each participant, addressing the potential non-linear narrative characteristic of a semi-structured design.

Results

• Twenty participants were interviewed face- to-face (n=9) or using a meeting platform (n=11).

• All participants were primary contact practitioners and were engaged in clinical practice across nine countries: Australia, the USA, the UK, Ireland, Norway, Sweden, Spain, New Zealand and India.

• Participants were primarily involved in managing adult elite (i.e. professional) athletes

• Of the 65% who had research experience, most (69.2%) had completed a PhD

Injury Prevention

Aetiology and Risk Factors in Preventing ‘Calves’

• Experts viewed identifying and combining information about the aetiology and risk factors of calf strain to be a key determinant of prevention

Do We Know Who Is at Risk of It Happening Again?

• Recurrence prevention proved challenging due to the practical complexities, as events don’t resulted from a single factor in isolation.

• The susceptibility to recurrence was primarily influenced by four factors deemed to have the most significant impact 👇

Can Risk Screening Tell Us Anything About ‘Calves’?

• Optimal screening strategies were personalised, taking into account historical, clinical, and performance data, while considering intrinsic factors like age and injury history.

“We’re going to get 10 or so new players in this year and have to screen them for the first time, and a player walks in, and I hate to be boring, but it would be injury history. Although we definitely do look at their movement because we have players who can’t even skip. They cannot two-footed skip for 30 s. I don’t know if I’d go straight to calf for that, but I’d like them to be able to skip. Can they jump rope for a sustained period of time? Can they do a simple movement?... If you can’t skip and we want you to run 14 k’s in a game, I’ve got a little bit of a mismatch there. We do things like calf rep max, body weight against the wall. I’d like to see people get to 30 on that. We metronome it.” (Expert 15).

• Experts in the field favoured using up to three objective tests alongside key subjective information for a comprehensive assessment.

• The single leg calf raise test was widely used to gauge foundational calf strength-endurance, but loaded strength testing was seen as more indicative of maximum capacity.

• Despite the recognised importance of strength, some experts highlighted its limitations in protecting against calf muscle strain injuries due to its inability to capture dynamic properties and diminishing value in compromised conditions.

• Additionally, there was a shift towards measuring power capacities during ballistic or plyometric tasks, emphasising the significance of repeated measures for a more accurate representation of performance over prolonged durations in running-based sports.

Athlete Monitoring to Prevent ‘Calves’ - Mitigating the Risk of ‘Calves’ Once Training and Competition Begins

• Calf capacity fluctuations were tracked using both subjective (tightness, pain) and objective (stretch tolerance, single leg calf raise, hopping) tests.

• Performance data, including dynamic exercises (e.g., reactive strength index) and GPS metrics (e.g., maximum acceleration speed, total volume), were examined to create a general risk profile for Calf Strain

• When an elevated risk was identified, mitigation strategies were employed, primarily involving reducing exposure to potential risk factors.

“It’s not just about exposing them, it’s about monitoring how they respond... sometimes they might have a bit of an adverse reaction to load. They might have some latent soreness after a heavy football session. But just be patient with them in those instances. Give them a session off and let them calm down before you go again. Whereas the guy who has never had a problem with his calf in the past, you can probably flog him in a footy session in the preseason, and if he gets calf soreness you can be more confident that he can probably push through the next football session with that soreness and not much will come of it. But maybe the guy that’s got, you know the ‘genetic risk for soft tissue injury,’ he’s the one you can’t afford to do that with. So just be patient, be sensible, in those instances. But that’s where individualised modifications occur on the run a little bit,” (Expert 18)

• Experts adjusted exercise selection if an increased risk was detected, avoiding activities that could worsen the situation, especially ballistic exercises and heavy calf strengthening.

• Limited exposure history posed a potential risk for calf strain, with three key flags:

  (1) Reduced training age

  (2) Recent interruptions like illness or injury

  (3) Restart after a break, such as the off-season.

  

• Monitoring running frequency was crucial while gradually increasing intensity and volume to prevent calf strains

“Frequency of running sessions is probably the thing that breaks them the most. Like when they first start to do back to back days,” (Expert 1)

• The choice of exercises was carefully monitored to avoid the risk of subsequent injuries

“It might take another month after they have returned to play before they are back up to normal loads. If you don’t want a recurrence, protect their workload even after they have returned to play...keeping them ‘off legs’ an extra day, and maybe protecting them on another, so they have recovery between major sessions and games, is really important,” (Expert 1).

Here’s an Idea: Why Don’t We Just Stop ‘Calves’
from Happening Instead?

• Initiating the prevention process often involves a 'needs analysis' to pinpoint the capacities and potential causes of calf strain in a sport, understanding the injury mechanisms and specific muscles affected.

“If you get them through preseason, where the program is well-structured, and they get good exposure to football, they get good exposure to running, it has consistent week-to-week progressions, you aren’t doing dumb jumps in week-to-week loading. You know, just well-crafted, common sense; you will get 95% of your guys through without calf injuries ever being a major issue for you”, (Expert 18).

• Continuous sports exposure plays a crucial role in safeguarding against calf strains by preparing the calf Muscle-Tendon Unit (MTU) for the sport's specific demands, considering that conventional off-field exercises cannot replicate the dynamic activity's relative load and loading rates.

• However, excessive or poorly timed exposure might elevate calf injury risk, regardless of well-designed preventive components.

• Adjusting load exposure is recommended, especially for older athletes or those with a history of calf problems or potential risk factors

• Plyometrics are acknowledged for providing significant protection to the calf, inducing adaptations that enhance the MTU's elastic function and reducing cumulative work by shortening ground contact times.

• Calf strengthening is emphasised as a cornerstone for building muscle capacity and resilience

“The trouble with calf strength is it is like a little magic thing that disappears on you. You haven’t done something, and you try to, especially in older men, and all of a sudden you can only do 5 calf raises. But you’ve been running and you’ve been doing all of this other activity”, (Expert 12

• Strength benchmarks vary across sports, with sprinters and rugby athletes aiming for at least 2 times body weight (BW), while Australian Football (1.0–1.5 × BW) and soccer (0.8–1.0 × BW) have lower benchmarks, prioritising strength-endurance.

• The single leg calf raise is universally recognised for training foundational strength-endurance and motor control, particularly in athletes with low training experience or notable weakness. Experts recommend at least 30 repetitions to fatigue and symmetry (asymmetry ≤ 10%).

“You probably do need a minimum level of calf capacity. As I said, our calf testing hasn’t been predictive in terms of the guys that can bang out 35 reps haven’t necessarily been immune. So I think it’s not necessarily a predictive marker, but having said that I think a guy that can only do 15 you just have to logically assume that capacity is going to be an issue for them”, (Expert 16)

• Criticism exists regarding the reliance on conventional strength training to prevent CMSI, as it often falls short in addressing the velocities and loading rates demanded during dynamic activities.

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