Nicholas Rolnick, The Human Performance Mechanic

01/12/2026

Each assessment can clue me into some of the potential drivers of .

Assessing spine range of motion is of course basic, but so underrated. It can offer information on willingness and tolerance to movement, whether there is a strong likelihood of mechanical block or if the client is hypermobile. It also serves as amazing test-retests for therapy to assess whether the treatment is improving immediately. Upper back mobility is another low hanging fruit because the spine is connected, so imagine one chain in the link not able to flow as freely, which could put additional strain in other areas such as the back.

Flexibility is assessed with the thomas test, which can clue me into potential regions that may need addressing. Prone cobra offers clues on lower back extension flexibility in non weightbearing which in the MAJORITY of clients is limited but can easily be improved. Last, hip rotation mobility, particularly into internal rotation could help with offloading some lower back strain.

I know I’ve missed a couple other things, but what would you also look at?

If you need some help, I’m taking a small number (1-2) of clients for and/or . Hit me up!

01/01/2026

2025 was a great year. Can’t wait for 2026.

What are you looking forward to?

12/31/2025

2025 was a great year for me.

I witnessed the birth of my beautiful daughter Kaia (KaiaTheMush), how amazing is at being a boss mom, moved into a new apartment big enough for my growing family, picked up massive steam (we blew past sales projections by ~40%!), continues to be a thought leader in education globally, I published 19 papers in , I overcame , and began making progress back to exercising. What a banner year filled with so many changes.

But what hasn’t changed is the support I have for my body and my feet with Arch Supports. I wear these everyday to work, around my apartment in my slippers, and even to high-end events in dress shoes. Possibilities are endless when you feel amazing support from the ground up with the right arch supports. I think I’ll continue to take these with me on whatever challenges life brings on in 2026.

alwaysforward

12/31/2025

What could be more ironic than someone talking about the necessity of 90 degrees in every joint then showing “optimal” with the hip at 120 degrees of flexion. Can’t make this up.

12/30/2025

Driving force through the first ray (1st met + hallux, the medial foot) stiffens the medial column, tensions the plantar fascia, and increases midfoot rigidity. That converts muscular force into ankle plantarflexion torque instead of spinning off. Net effect: a longer, stiffer lever and a more favorable plantarflexor moment arm to drive

When load drifts to digits 2–5, the forefoot stays compliant. Ground reaction force is absorbed by MTP dorsiflexion, toe flexors, and intrinsics. Force is dissipated, ankle torque drops, and calf demand falls leading to a pretty substandard calf stimulus.

Play around with the cues, but try to keep the toes relaxed and the big toe engaged to transfer that force to the inside of the foot, and take your calf gains to the next level.

Bonus: Add a stretch to dissipate achilles influence and only go to neutral ;)

09/20/2025

Do only the last 5 reps before failure “count” for muscle growth? 🤔

The “effective reps” model claims that only reps in close proximity to muscular failure stimulate hypertrophy, since that’s when motor unit recruitment, bar speed, and mechanical tension peak.

But research tells a more nuanced story:
✅ Meta-analyses show similar hypertrophy with both low- and high-load training, as long as effort is sufficient.
✅ Blood flow restriction (BFR) studies found that stopping at ~75% of total reps (well before failure) produced similar growth to training to failure.
✅ Multiple repetition schemes across different BFR contexts yield comparable results.

What does this mean?

Proximity to failure probably does matter, especially for advanced lifters where the margin for error is smaller. However, to what end is still up for discussion.

For beginners, the “window” for effective hypertrophy is probably much wider than the simplified “last 5 reps only” idea. More room for growth while operating further from failure.

Training to or near failure is definitely a useful way to track effort and ensure progression, but it’s not the only way to grow (although I think it still is the best way).

I prefer lower repetition schemes as you will optimize strength and connective tissue as well. Personally, 6-12 reps is a nice sweet spot for me and my clients.

🔑 Takeaway:
Don’t obsess over hitting a magical number of “growth reps.” Instead, focus on training with sufficient effort, accumulating quality volume, and progressing over time. The hypertrophy window is probably wider than social media often tells us.

What are your thoughts? Let’s discuss.

07/29/2025

🔬 Does Having A Enhance Outcomes Associated with ?

A new 2025 RCT by Gavanda et al. compared the outcomes of supervised (in-person), app-guided, and self-directed (PDF) resistance training over 10 weeks in trained men and women (n = 79). Each group performed the same full-body training program 3x/week, differing only in the level of guidance and feedback.

📈 Key Findings:

Supervised training (SUP) led to the greatest gains in squat strength (+26.6 kg), fat-free mass (+1.4 kg), and well-being (+15.7 pts on WHO-5).

All groups improved bench press 1RM, but only the supervised group showed significantly superior squat improvements—highlighting the value of real-time technical feedback in complex, multi-joint lifts.

Adherence rates were highest in SUP (88%), compared to APP (81%) and PDF (52%).

Supervision satisfaction (S-SRQ) was also significantly higher in SUP vs APP.

Fat mass increased slightly in the APP group, possibly due to lack of nutritional control and/or compensatory eating.

💡 Implications:
Direct supervision from a enhances , neuromuscular adaptations, psychological well-being, and accountability—especially in technically demanding exercises. While app-based training showed promise for accessibility and moderate gains, it lacked the effectiveness of live coaching - which can be attributed to possibly many reasons, but most likely you want to be a beast in person and not embarass yourself. That’s motivation enough.

📱 Realistically, hybrid models combining digital platforms with periodic human feedback may offer scalable alternatives where consistent in-person coaching is not feasible. Thoughts?

📚 Source: Gavanda et al., J Strength Cond Res, 2025.

06/30/2025

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04/23/2025

Thanks to for the trust in educating the future of our profession in . The trust is invaluable. It means being able to quite literally change clinical practice. It means getting more clinicians familiar with and the importance of muscle . It means making a difference beyond 1-1 patient interactions.

Can’t put a 💰 on influence. I don’t take that for granted and hope to continue to live through example.

04/21/2025

Aerobic exercise has been shown to induce muscle hypertrophy when combined with blood flow restriction (BFR).

That alone is surprising.

Even more perplexing?

Studies like Kim et al. (2015) show no significant differences in muscle activation (EMG) between aerobic BFR and non-BFR conditions whereas Kilgas et al. (2022) showed some pressure-dependent reduction (80% LOP > 60% LOP) in post-exercise maximal voluntary isometric contraction but no loss in high-intensity or low intensity exercise without BFR.

So what gives?

Shown above is a conceptual model of motor unit recruitment that may help explain this paradox.

Surface EMG reflects the total activity of motor units near the electrode—but it doesn’t tell us:

Which fibers are firing

How fatigued they are

Or whether higher-threshold motor units are being pulled in over time

When BFR is added, metabolic stress and local hypoxia rise. This accelerates fatigue in already-recruited fibers, which slows contraction speed and increases mechanical tension—two key hypertrophy signals.

Even if EMG readings appear unchanged, the internal environment is dramatically different.

🧾 A few studies showing hypertrophy with aerobic BFR:

Abe et al. (2006, 2010) – Walking/cycling protocols → +5–8% muscle CSA

Chen et al. (2022) – Running with BFR → +3.7% thigh mass

Clarkson et al. (2017) – Older adults gained size and strength with BFR walking

Low-intensity aerobic BFR likely recruits higher-threshold motor units earlier than standard cardio and to a much less degree than is likely with resistance exercise.

Understanding the force-velocity relationship, motor unit recruitment differences between low- and high-load exercise, as well as other adjunctive markers that may be associated with a heightened physiological environment that may accelerate fatigue accumulation may help inform the hypertrophic potential of aerobic exercise with BFR.

PS: These are part of a long-form article that will be released on my patreon.

04/20/2025

Happy Easter and a reminder we have $20 off plus free shipping on our revolution 2.0 through tonight using code EASTER…sportgrips.com. Now with this thought experiment.

Minimizing fatigue and optimizing motor unit recruitment is essential for maximizing muscle .

This chart shows a hypothetical model of muscle hypertrophy comparing low-load (~90% motor unit recruitment) and high-load (~100%) resistance training over a 2-year span.

Up to 26 weeks, gains appear nearly identical — the low-load group achieves ~95% of the growth seen in the high-load group. Statistically, there’s no significant difference at this point (p = 0.34, Cohen’s d = 0.21). For anyone training recreationally or in a rehab setting, this might seem like good news.

But as training continues, the compounding advantage of full motor unit recruitment with heavy loading starts to show. By week 52, the difference becomes significant (p = 0.005, d = 0.74), and by week 104, it’s even more pronounced (p < 0.001, d = 0.95). This reflects the accumulating benefits of maximizing tension and mechanical load over time.

Assumptions in this model include: – Equal training frequency and effort (sets to failure or near-failure in both groups)
– Trained male participants with no baseline group differences
– Growth potential in low-load group capped at ~90% due to partial motor unit recruitment
– Nonlinear hypertrophy trajectory over time
– Muscle growth measured via CSA or thickness at multiple intervals

Bottom line: while low-load training can work well in the short term, especially when taken close to failure, it’s unlikely to match high-load training over the long haul—especially when the goal is maximizing hypertrophy.

If you’re in this for years, not weeks, that last 10% matters and is something we probably don’t get real clarity on in 99% of the durations of the studies.

helped me out with the illustration.