Build for Health with Srdjan Injac

More free fitness instruction exists right now than at any point in history. You can watch a qualified coach teach a squat at 2 a.m. for nothing. And the share of American adults who strength train twice a week has barely moved. In 1997, about one in five met the guideline. By 2018, it was about 27%. So where did all that content go? This episode follows the incentives. A creator has to post something new every day to stay in the feed. A body getting stronger needs roughly the same few things, week after week, for months. When those two clocks run side by side, the advice changes faster than anyone can follow it. One Australian study of 300 healthy-lifestyle videos found most of the information misleading, and the creators with no relevant qualifications got it right less than one time in twenty. A study of news on Twitter turned up something less comfortable. When researchers took the bots out, false stories still spread faster than true ones. People did that part. Then the gym floor: what happens when someone follows a downloaded program through shoulder pain because the app says four sets, and what researchers saw when women looked at fitspiration images and then got on a treadmill. There's also a lightning round through the trends in a real feed this week: Hyrox, creatine, 75 Hard, cold plunges, and anything ending in "maxxing." Signal or noise? It ends with a number short enough to fit on an index card. Links & Notes "Eat Like Me = Look Like Me": A Content Analysis of Healthy Lifestyle, Nutrition and Clean Eating Social Media Content(Porteous, Kemps, Powell & Prichard, Journal of Technology in Behavioral Science, 2026). The Australian study of 300 TikTok and Instagram videos: 68% of the information was misleading or deceptive. The Spread of True and False News Online (Vosoughi, Roy & Aral, Science, 2018). The MIT study: false news was 70% more likely to be retweeted, and the gap held with bots removed. The Effect of Instagram #Fitspiration Images on Young Women's Mood, Body Image, and Exercise Behaviour(Prichard et al., Body Image, 2020). The treadmill study. Trends in Adherence to the Muscle-Strengthening Activity Guidelines in the US Over a 20-Year Span(Calatayud et al., General Hospital Psychiatry, 2023). 19.8% in 1997, 27.2% in 2018. Trends in Muscle-Strengthening Exercise Among Nationally Representative Samples of United States Adults Between 2011 and 2017(Bennie et al., Journal of Physical Activity and Health, 2020). 29.1% to 30.3% over six years, in a sample of 1.7 million adults. Episode 39: Stress, Cortisol, and Your Gains. For anyone eyeing a cortisol cocktail. Episode 22: Stop Collecting Sore Joints and Start Making Progress: Programming 101. For when you're picking the one program you'll stick with. Episode 7: Trainer Red Flags, Green Flags, and Real Talk. More on sorting out who knows what they're talking about. Work with Srdjan and the team at ELEV8 Fitness in Portland, Oregon. Submit your questions to the show!

You can do everything right in the gym and still undo it on the couch at midnight. Lifting doesn't build muscle while you're lifting. It damages muscle and sends a signal. The rebuilding comes later, mostly while you're asleep, and it depends on conditions that a short night takes away. This episode goes inside that night shift. Deep sleep brings a major pulse of growth hormone, but calling it "the muscle-building hormone" sells short what it's actually doing. Testosterone and the nervous system have their own overnight jobs, and strength turns out to be partly something your brain has to practice in its sleep. Then the harder question: what does a pattern of short nights cost someone who's training and dieting at the same time? One number from the research works out to roughly an extra meal a day, eaten without deciding to. From there it's on to whether the weekend catch-up most of us rely on actually balances the books, what a sleep tracker is good for when it's obviously wrong about last night, and a practical list for people who've slept badly for years. This episode is general information, not medical advice. If you have a diagnosed sleep disorder, work with a specialist. Links & Notes The Effects of Partial Sleep Deprivation on Energy Balance (Al Khatib et al., European Journal of Clinical Nutrition, 2017). The meta-analysis behind the 385-calorie number: short sleep raised daily intake with no change in calories burned. The Effect of Acute Sleep Deprivation on Skeletal Muscle Protein Synthesis and the Hormonal Environment(Lamon et al., Physiological Reports, 2021). One night without sleep lowered muscle protein synthesis by 18%. Sleep Curtailment in Healthy Young Men Is Associated with Decreased Leptin Levels, Elevated Ghrelin Levels, and Increased Hunger and Appetite(Spiegel et al., Annals of Internal Medicine, 2004). The two hunger hormones from this episode. Ad Libitum Weekend Recovery Sleep Fails to Prevent Metabolic Dysregulation (Depner et al., Current Biology, 2019). The study on weekend catch-up sleep. Episode 40: Rest Is Not One Thing. The four kinds of recovery, plus more sleep research. Episode 5: Recovery Is Not a Reward. Where this conversation started. Work with Srdjan and the team at ELEV8 Fitness in Portland, Oregon. Submit your questions to the show!

Most of us walk into the gym assuming the body is on duty and the brain has the hour off. It's the other way around. Every squat starts as an electrical signal. The awkward first weeks of a new movement aren't weak muscles, they're a nervous system learning a skill. Strength, it turns out, is partly something you know how to do. That's the door into a bigger question: what does lifting do for the organ running the show? This episode covers the research connecting resistance training to executive function and memory, why exercise reaches the brain through blood vessels and blood sugar as much as through muscle, and a trial in adults over 55 that pitted heavy lifting against computerized brain training. The brain training didn't win. Then the part that matters most as we age: balance, falls, and why the speed of a correction can matter as much as raw leg strength. What can be trained, what can't, and where a fall in your seventies fits in the dementia picture. Aging is inevitable. Weakness is not. Links & Notes Visit ELEV8 Fitness PDX and Find Your Next Trainer! Submit your questions to the show!

Training is the stimulus. It is not the adaptation. That happens later — in the hours we treat as leftover time, and describe with words that all mean absence: rest day, off day, recovery day. This week Pete brings Srdjan a piece of research that has nothing to do with the gym and everything to do with it. In 2007, Sabine Sonnentag and Charlotte Fritz published the Recovery Experience Questionnaire, built on a puzzle they kept running into: hours off didn’t predict who came back restored. Two people take the same weekend. One returns ready. One returns wrecked. Their answer was that recovery isn’t one thing — it’s four, and they don’t substitute for each other. Psychological detachment. Relaxation. Mastery. Control. If you spend all day being told what to do, lying on the couch won’t fix it; you need a rest that hands you back the controls. Srdjan takes that framework into the gym and it holds up uncomfortably well. He walks through what’s actually happening in your body after a hard session — glycogen, protein synthesis, the twenty-four to forty-eight hour repair window — and makes the case that soreness is a lousy measurement of recovery, because different systems come back online at different speeds. Muscles, energy stores, connective tissue, nervous system. None of them are on the same clock. Recovery isn’t separate from training. It is the training. Let’s build. Links & Notes The Recovery Experience Questionnaire (Sonnentag & Fritz, 2007) — the four-factor model of detachment, relaxation, mastery, and control. Free full text, and the paper that kicked off this whole episode. Also on PubMed. Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity (Nedeltcheva et al., Annals of Internal Medicine, 2010) — the metabolic ward study, 8.5 versus 5.5 hours of sleep opportunity. Effect of 1 Week of Sleep Restriction on Testosterone Levels in Young Healthy Men (Leproult & Van Cauter, JAMA, 2011). The Effects of Sleep Extension on the Athletic Performance of Collegiate Basketball Players (Mah et al., Sleep, 2011) — every player improved on every measure. Gaining More From Doing Less? (PeerJ, 2024) — the thirty-nine-lifter deload study. Free full text. Work with Srdjan and the team at ELEV8 Fitness in Portland, Oregon. Submit your questions to the show!

Cortisol gets described online as the thing standing between you and the body you want. It's actually the hormone that gets you out of bed. It runs on a daily curve, highest in the morning and lowest at night, and it regulates blood sugar, blood pressure, inflammation, and how much energy the body makes available when something demands it. Exercise raises it. That's the point of exercise. A hard session raises cortisol for a few hours, then it settles. Chronic stress never allows the settling. The body doesn't keep separate accounts for work, caregiving, money, bad sleep, and training. It adds them up, and when the total outruns the capacity to recover, strength stalls and motivation goes, and the natural conclusion is that the program isn't working. An acute training spike is a different condition than chronically elevated cortisol, and treating them as the same thing is how people end up buying a supplement to solve a sleep problem. "Cortisol belly" turns out to be a product category. Five hours a night turns out to have a price. Plus: the case for walking into the gym anyway on the worst days. Links & Notes On cortisol's normal daily rhythm Cortisol Awakening Response: Regulation and Functional Significance — Endocrine Reviews The circadian system modulates the cortisol awakening response in humans — Frontiers in Neuroscience On exercise, cortisol, and stress regulation Effects of a 12-week endurance training program on the physiological response to psychosocial stress in men: a randomized controlled trial — Journal of Behavioral Medicine The effects of exercise intensity on the cortisol response to a subsequent acute psychosocial stressor On "cortisol belly" The 'cortisol belly' myth: when diet culture is rebranded as wellness — The Conversation 9 Myths About the 'Stress Hormone' Cortisol — TIME Routine Screening for Cushing's Syndrome Is Not Required in Patients Presenting with Obesity On sleep Sleep loss lowers testosterone in healthy young men — UChicago Medicine (Leproult & Van Cauter, JAMA 2011 — the 10–15% finding) Sleep loss boosts hunger and high-calorie food choices — University of Chicago Impact of Five Nights of Sleep Restriction on Glucose Metabolism, Leptin and Testosterone in Young Adult Men — PLOS One On energy availability and reproductive hormones Hypogonadism in Exercising Males: Dysfunction or Adaptive-Regulatory Adjustment? Show links ELEV8 Fitness Submit your questions to the show!