A single resistance training session affects several systems at once. Muscle protein synthesis and energy expenditure stay elevated into recovery, glucose uptake and insulin sensitivity improve, pain sensitivity and state anxiety drop, and aspects of executive function sharpen. According to a 2026 narrative review by James P. Fisher in PeerJ, these responses are real but temporary, and they should not be treated as adaptation in themselves. For lifters, the practical point is that the session is the signal, and only repeated sessions logged over months show whether adaptation is happening.
This matters because most strength training research and hypertrophy study coverage focuses on long-term outcomes such as strength, muscle size, and bone health. Fisher's review looks at the hours after a single workout instead. It also offers a useful correction to a common habit: judging a session by how it feels.
Key Finding
One bout of resistance exercise produces responses that overlap in time across endocrine, metabolic, vascular, pain, psychological, cognitive, and sleep-related domains. The review stresses that these effects do not all have the same level of evidence. Some have been directly observed. Others are proposed mechanisms or tentative hypotheses.
The central caution is explicit. Acute responses should not be assumed to represent adaptive remodelling or to directly cause the chronic health benefits of training.
Study Details
This is a narrative review, not an experiment. Fisher synthesized existing literature to describe what happens across the body after a single session.
- Design: narrative review using iterative database and reference-list searches
- Evidence prioritized: primary human studies that directly measured acute responses
- Supporting evidence: systematic reviews, meta-analyses, and mechanistic literature
- Scope: one bout of resistance exercise, not training programs over weeks or months
The distinctive contribution is integration. Researchers usually study these responses in separate silos, such as endocrinologists studying myokines and psychologists studying anxiety. This review puts them on the same timeline.
Results: What Happens After One Session
The abstract summarizes responses across seven domains. Here is what the review reports, in plain English.
Metabolic and Muscle Responses
- Muscle protein synthesis may remain elevated during recovery. This is the acute process that repeated training is thought to build on for hypertrophy.
- Post-exercise energy expenditure may stay above resting levels for a period after the session.
- Glucose uptake and insulin sensitivity are enhanced after resistance exercise.
Myokines and Signalling
Contracting skeletal muscle releases myokines and other signalling molecules that may act on other tissues. This research area is active, and the review places some proposed systemic roles in the more tentative category.
Pain, Mood, and Cognition
- Exercise-induced hypoalgesia: pain sensitivity can drop temporarily after a session.
- State anxiety can decrease. State anxiety is how anxious you feel in the moment, not a lasting trait.
- Aspects of executive function and cognitive performance can improve acutely.
Sleep and Neurophysiology
Resistance exercise may influence sleep continuity and neurophysiological activity. The review's wording here is deliberately hedged, so this is the least settled of the domains.
Limitations
The review is useful, but its conclusions have clear limits.
- It is a narrative review rather than a systematic review. Its search strategy was iterative, not pre-registered, so study selection is more open to author judgment and the findings cannot be pooled into effect sizes.
- The evidence quality varies by domain. Insulin sensitivity and protein synthesis responses rest on stronger direct evidence than claims about myokine signalling or sleep, and the review says so itself.
- Acute does not mean chronic. The review explicitly avoids claiming that these short-term responses explain long-term adaptation. How repeated acute responses add up over time is still an open research question.
What This Means for Your Training
The most useful idea here is a distinction many lifters blur: what a session does to you today versus what your training does to you over a year. Evidence-based training means keeping those separate.
1. Stop grading sessions by how they feel
The pump, the post-workout calm, and the sharper focus are all acute responses. They tell you a session happened, not that it moved you forward. A session can feel excellent and add nothing to your progression, and a flat, unpleasant session can be exactly the right one.
Use objective markers to judge progress:
- Load and reps on your main lifts, compared over 4-8 weeks rather than session to session
- Total hard sets per muscle group per week
- Rep performance at a given load, such as getting 3x8 at a weight that was 3x6 last month
2. Distribute the stimulus
If the acute signals, especially elevated protein synthesis, are what repeated training builds on, then how often you create them matters. Research consistently suggests that spreading weekly volume across two or more sessions per muscle group works at least as well as cramming it into one long session. For many lifters, three or four shorter sessions are easier to sustain than two marathon ones, and sustainability is what turns acute responses into chronic ones.
3. Respect hypoalgesia during the session
Exercise-induced hypoalgesia is pleasant, but it has a downside. If pain sensitivity drops as you warm up, a joint niggle that hurt at set one may feel fine by set four. Note discomfort early in the session, before it is dampened, and record it alongside the lift. A pattern of notes across several sessions is more useful than any one session's impression.
4. Use the acute benefits when they help
Acute effects don't drive long-term progress, but they still affect your day. If a session reliably lowers your anxiety or improves your focus, scheduling it before demanding cognitive work is a reasonable personal experiment. If you manage blood glucose for medical reasons, the insulin sensitivity response is worth discussing with your clinician rather than self-prescribing around.
5. Treat sleep effects as individual
Because sleep findings are tentative, don't overhaul your schedule based on generalizations. If you train in the evening, compare sleep on training days with rest days for a few weeks before deciding whether timing matters for you.
How This Fits Into Your Training Log
Acute responses fade within hours, but logged sets accumulate. Kenso's rule-based progression engine reads your recorded load and reps across sessions, not how a workout felt, so you can let Kenso set your next session's targets from logged performance.
The Bigger Picture
Fisher's review gives lifters a more accurate picture of a single workout. Every session sets off a cascade of metabolic, hormonal, psychological, and neurological changes, which helps explain why training often feels worthwhile on the same day. But the review is careful to say that this cascade is not the adaptation.
Adaptation is what accumulates when those acute signals are repeated consistently over months. That makes your training history the record that matters. Kenso's AI Coach can read that history and help you see whether your logged numbers are moving, regardless of how any individual session felt.
FAQ
Does muscle protein synthesis stay elevated after a workout?
Yes. Fisher's review notes that muscle protein synthesis may remain elevated during recovery after a single resistance session. Repeated training is thought to build on this acute response, but the review cautions that the acute response alone does not equal hypertrophy.
Is the pump a sign that a workout is effective?
Not on its own. The pump is a short-term response, and the review explicitly warns against treating acute responses as evidence of adaptation. Progress is better judged by tracked performance, such as load, reps, and weekly sets, over several weeks.
Can one strength training session reduce anxiety?
The review reports that acute resistance exercise can reduce state anxiety, meaning momentary feelings of anxiety. This is a temporary effect and should not be read as treatment for an anxiety disorder.
Why does pain feel lower partway through a lifting session?
This is likely exercise-induced hypoalgesia, a temporary drop in pain sensitivity after or during exercise. It is worth noting any discomfort early in a session, because the sensation may be dampened by later sets.
Does lifting improve sleep?
The evidence is tentative. The review states that resistance exercise may influence sleep continuity and neurophysiological activity, but this is among its least settled domains. Comparing your own sleep on training and rest days is more informative than relying on general claims.
Start Logging the Signal That Lasts
One session changes how your body and mind function for hours. Consistent sessions change what you're capable of over years. Kenso helps you track the second part, with a progression engine built on your logged performance and an AI Coach that understands your training history. Download Kenso on iOS and train with intention.
Citation
Fisher JP. Beyond the pump: a narrative review of the acute molecular, metabolic, and neuropsychological responses to a bout of resistance exercise. PeerJ. 2026. doi: 10.7717/peerj.21827. PubMed: https://pubmed.ncbi.nlm.nih.gov/42898926/