Jem Arnold
@jem_arnold
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PhD candidate 🇨🇦 physiotherapist. Sport vascular conditions, performance testing, mNIRS. Treat declarative statements as questions?
Vancouver, Canada
Joined January 2016
Just published from my (eventual) PhD thesis 🔖 Review of conservative treatment (CTx) for Flow Limitations in the Iliac Arteries (FLIA, endofibrosis) and proposal of Return to Sport (RTS) guidelines after surgery Here is what we learned🧵/14
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🚴♂️💪 New meta-analysis (54 studies!) shows HIIT & sprint intervals can modestly increase lean mass & muscle endurance vs. regular cardio 🧬 — but for max strength & growth, lifting still wins 🏋️♂️ 👉Combine HIIT + strength for the best of both worlds ⚡ https://t.co/lAeIc90rfp
mdpi.com
High-intensity/sprint interval training (HIIT/SIT) improves aerobic and anaerobic performance, but it is unknown if HIIT/SIT increases strength, muscle mass/size, and muscle endurance (ME). We aimed...
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This exploratory study suggests that both 2 and 3 weekly sessions of 4 × 4-min HIIT can provide a similar stimulus for cardiorespiratory improvements in recreationally active individuals, with diminishing returns for increasing frequency beyond twice weekly.
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Vallieres makes history as first Canadian to win World Championships. https://t.co/goSV4t21wL
escapecollective.com
An underdog victory for Magdeleine Vallieres who read the race to perfection, and the favourites waited too long to act.
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Get to know brand-new world champion Magdeleine "Mags" Vallieres Mill through this 2023 interview, back when the Canadian was still learning a lot about who she was and where her strengths lay as a pro road cyclist. https://t.co/AzDDs7pbpy
escapecollective.com
Magdeleine Vallieres Mill is finding her feet in the WorldTour, and loving every second of it.
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(7/8) These findings demonstrate that highly trained females and males have similar muscle O₂ extraction and perfusion per kg LBM. However, females’ 10% lower haemoglobin concentration results in lower LBM-normalised O₂ delivery and VO₂max.
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1/ Interval training is a cornerstone of endurance performance. We often stick to stock standard session design, but new research highlights various manipulations to maximise the adaptive stimulus, from interval duration & intensity to recovery dynamics. #HIIT #SportsScience 🧵👇
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can anyone recall the ancient magicks of recording high frequency pedal forces with Velotron? 🧙♂️ Is this possible? It clearly knows about forces through each pedal stroke, but can we export it somewhere? Looking for high sample rate options for a study
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Another great 🧵 from @RodSiegel Consider that most of our O₂ gets delivered to our working muscles during blood flow *between* contraction cycles. Blood flow can be *retrograde* during contractions. Classic model here from Rådegran 1997 1/4 tying some threads together👇
6/ Then, there’s the duty cycle; the work-to-rest ratio within each stride/stroke. Bundle & Weyand (2012) explain that running has a short “work” (ground contact) & longer “rest” (airborne) phase, slowing fatigue development compared to cycling’s longer “work” phase 📉 #DutyCycle
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When does resistance exercise become endurance exercise? 🏋️↔️🏃 It might depend on the critical occluding tension in our muscles 💪🩸 🧵/ 📚link👇 A Critical Occluding Tension Phase Transition Occurs Between 30-40% 1RM in Dynamic Knee Extension Exercise
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Which we will be building on looking directly at intramuscular pressure and muscle oxygenation during transition exercises between resistance and endurance training (knee extension & cycling models) 4/4 https://t.co/ewaDZc3bq1
When does resistance exercise become endurance exercise? 🏋️↔️🏃 It might depend on the critical occluding tension in our muscles 💪🩸 🧵/ 📚link👇 A Critical Occluding Tension Phase Transition Occurs Between 30-40% 1RM in Dynamic Knee Extension Exercise
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And from some reproduction work we did looking at intra-pedal stroke pedal forces and oxygenation 3/4 https://t.co/MJrRLazFVX
With Train Red #NIRS and Lode ergometer pedal force recording at 100 samples per second we can evaluate #muscleoxygenation responses within a single pedal cycle Nice illustration from my colleague's project, some thoughts below 🧵
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Contraction squeezes muscle like a sponge. Blood gets pushed out. Relax opens the sponge up and sucks blood in e.g. muscle oxygenation during cycling. Takaishi 2002 2/4
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Another great 🧵 from @RodSiegel Consider that most of our O₂ gets delivered to our working muscles during blood flow *between* contraction cycles. Blood flow can be *retrograde* during contractions. Classic model here from Rådegran 1997 1/4 tying some threads together👇
6/ Then, there’s the duty cycle; the work-to-rest ratio within each stride/stroke. Bundle & Weyand (2012) explain that running has a short “work” (ground contact) & longer “rest” (airborne) phase, slowing fatigue development compared to cycling’s longer “work” phase 📉 #DutyCycle
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1/ Sports Scientists often criticise how other sports train. We hear things like "why do swimmers train such huge volumes compared to runners racing similar durations?" It’s not just coaching tradition & culture; it's about physiological & biomechanical demands 🧵👇#SportsScience
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Figure @SitkoSebastian et al, 2022. Functional Threshold Power as an Alternative to Lactate Thresholds in Road Cycling https://t.co/gfV8mbwYmn
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Saw a question "what %FTP should my first threshold be at?" How do we begin to guess? Start with a prediction interval, not a falsely precise point estimate Data from @SitkoSebastian 2022 might give us that starting estimate (link below 👇)
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This was a super interesting read and it also reminded me of the importance to account for heteroskestadicity (not sure I wrote it correctly). In many areas of research even when two things are linearly correlated, the variance at the extremes might be very difference.
Garmin probably has a much larger training dataset of “average” athletes than highly trained endurance athletes with VO2max >60 ml/kg/min So in this experiment at least, the estimated VO2max accuracy was better for lower fitness participants, and worse for higher fitness 11/
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@jem_arnold @Nyborger_Nybo @jwhitfie @EvanDunfee I’d love to know a bit more about the biomechanics and impact of race walking compared to running. Does the technique allow for less impact per strike? Would it be useful for overuse injury? Is it useful to get walkers to build aerobic load? Useful for cyclists traveling w/o
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