What's the Best Way to Exercise for Health and Longevity - 2.5 hour Roundtable with 2 PhDs

Greg details that the '10 sets per muscle per week' recommendation from meta-regression counts compound movements like rows as sets for lats and biceps, so dedicated isolation work is not required to hit that number for every muscle. He and Nick stress the importance of intentionality: moving the implement quickly recruits high-threshold motor units and builds power without separate drills. Siim adds that he shifted from high-volume bodybuilding to lower-volume, strength-focused training and saw equal maintenance and better strength. Greg also emphasizes that relative strength (strength per body weight) is crucial for daily functioning, and that training at long muscle lengths (e.g., loaded stretching, isometrics at bottom of squat) can improve flexibility and strength throughout the range of motion, with some evidence of vascular benefits. Periodization, including 'deload' weeks where volume is sharply reduced, is recommended to manage fatigue and prevent overtraining.

Greg explains the principle: intermittent work allows more total volume at intensities that maximally stimulate VO2max improvements. He advises that modality matters: cycling produces less muscle damage and interference than running. Nick points to extensive research on HIIT's effects on VO2max and overall health. Both agree HIIT should be the default endurance prescription for time-poor individuals, with continuous moderate or zone 2 work layered in only if recovery allows and more volume is desired. Greg also notes that some endurance training at moderate intensity might confer unique central adaptations (larger, more compliant left ventricle) but the evidence is tentative. Siim uses sprinting once a week for power and cardiorespiratory stimulus, but chiefly relies on strength training and zone 2 for recovery.

Siim uses zone 2 cycling on his non-resistance days because it doesn't hinder his calisthenics or leg recovery, and he still sees aerobic benefits over time. Greg emphasizes that for the 83% of the population not meeting minimum exercise guidelines, spending time on zone 2 is an inefficient starting point. The physiology may differ for elite endurance athletes accumulating 10-20 hours/week, but not for the average person. Both acknowledge that recreational hiking and walking serve a similar purpose and may be more enjoyable. Greg's meta point: if you're already doing intense training, adding some zone 2 is fine; if you're doing nothing, more intense work gives the biggest bang for the buck.

Greg highlights research showing that short post-prandial walks can meaningfully lower blood glucose responses. He ties this to the broader benefit of walking for metabolic and vascular health. Combined with step count goals (around 7,000–8,000/day), this small habit can be a simple entry point for people who don't exercise. Siim agrees that walking is a low-barrier activity that even highly active people can use to increase daily energy expenditure and break up sedentary time.

Greg explains that lengthy muscles produce more force at long lengths and transfer well to shorter lengths, making them a time-efficient way to build mobility and muscle simultaneously. He cites research on isometric training reducing blood pressure, making this type of loaded stretching a multipurpose intervention. Examples include dumbbell goblet squat hold, pec stretch with dumbbells, or stiff-leg deadlift holds. He suggests combining with full range-of-motion resistance training to maximize flexibility and strength. Siim adds that finishing a set of bench press with a pec stretch could provide an additional hypertrophy stimulus.

Nick stresses that balance exercises are crucial for older individuals to prevent falls that can lead to a hip fracture and a vicious cycle of frailty. Greg adds that many compound exercises already challenge balance, so dedicated Bosu balls or slacklining are usually unnecessary. Simple tasks like standing on one leg or practicing the 'flamingo test' (1 minute) can assess and train balance. Rotational movements (e.g., kettlebell work) are often missing from traditional gym routines and can improve functional balance. The key is to challenge the vestibular and proprioceptive systems without over-weighting the movement.

Greg points out that many people will develop common restrictions from sitting: tight hip flexors, rounded thoracic spine, and internally rotated shoulders. He advocates for 'smart strength training through a full range of motion' as the best flexibility intervention, supplemented with targeted stretches. Loaded stretches (e.g., goblet squat hold) can simultaneously stretch and strengthen. He notes that Olympic lifters exemplify how heavy lifting through full ranges builds impressive mobility without dedicated stretching routines. Siim agrees, adding that rotational work (often neglected in gym routines) can also improve mobility.

Siim references meta-analyses showing the sweet spot around 7,000–8,000 steps. Greg notes that for older adults, 7,000 may be plenty, while younger individuals might pursue higher counts but the benefits taper. Both advocate for using walking as a way to break up sitting, get daylight exposure for circadian health, and enter a restorative mental state. Greg discourages always listening to podcasts or music; being in nature without input can boost creativity and emotional regulation. Siim mentions that heavy exercisers don't need to stress about hitting 10k steps, as their training volume already provides the health benefits.

Siim and Greg both note that for individuals already physically active (e.g., manual laborers), nutrition optimization may yield more marginal gains. However, for the typical desk-bound person, improving exercise habits is the single highest-leverage health intervention. Siim emphasizes that being unable to do a few pull-ups or getting winded on stairs indicates where the real attention should go. Greg adds that epidemiological data show a dose-response protective effect of physical activity against all-cause mortality, making exercise a far more potent tool than any supplement. The overarching message: audit your physical capacity before spending mental energy on finer nutrition details.

Greg explains that muscle memory and the body's adaptive capacity mean you can push hard for a period to build reserves, then scale back significantly—even to very minimal doses of resistance training—while retaining roughly 90% of what you've built. This has profound implications for life-long adherence: you don't need to maintain peak volume forever. Nick adds that 'use it or lose it' applies broadly; even in microgravity, lack of loading causes rapid bone and muscle loss, illustrating that some stimulus is always needed but the dose can be low once the base is set. Siim ties this to aging: you can exceed youthful function if you stimulate systems appropriately, making exercise a tool not just to slow decline but to elevate capacities above baseline.

Nick argues that later in life (50+), strength and power become paramount because they directly impact the ability to get up from a chair, catch oneself from a fall, or maintain independence. Muscle mass, while beneficial for metabolic health and glucose disposal, is a secondary outcome that often 'comes along for the ride' when training for strength. Greg underscores that relative strength (strength per kg body weight) is key, and that absolute strength also matters for tasks like lifting luggage. They both note that older individuals can gain strength at similar relative rates as younger people, even if hypertrophy is slower, which reinforces the importance of strength-oriented training irrespective of age. Siim adds that excessive body fat with large muscle mass is not optimal, advocating for lean body composition and strength-focused training in the 5-10 rep range.

Greg explains that VO2max captures body composition (relative value), cardiac output, vascular function, and more. A high relative VO2max generally indicates favorable health habits, but you could artificially raise it (e.g., via drugs) without improving health, or lower it temporarily by giving blood while actually reducing cardiovascular risk from iron overload. Siim adds that the key is stability over time: if you maintain VO2max as you age, you're actually fighting the natural decline, which is a better sign than a high peak that plummets. A VO2max of 50 ml/kg/min is achievable for many without extreme exercise and is associated with significantly lower mortality. Greg recommends simple field tests like the Cooper 12-min run or online calculators (worldfitness.org) for those who don't want lab testing.

Greg traces the zone 2 hype to conversations between Peter Attia and Iñigo San Millán, a cycling coach whose elite athletes need high volumes of low-intensity work to accumulate training without burnout. For the 83% of adults not meeting minimum activity guidelines, he argues that HIIT (e.g., Norwegian 4x4) or sprint interval training provides a stronger cardiorespiratory stimulus by allowing accumulation of time near VO2max via intervals. Zone 2, typically around 3 METs, is simply not intense enough to drive rapid improvements. However, Siim points out that he uses zone 2 cycling as active recovery between resistance training sessions to add volume without compromising recovery or causing muscle damage. Greg acknowledges that for those with plenty of time or endurance athletes, zone 2 has a role, and there may be subtle long-term cardiac adaptations (e.g., larger, more flexible heart) that HIIT does not replicate, but the data are still unclear. For the average punter, triage demands higher-intensity work first.

Greg references Frank Booth's work cataloging sedentary-related disease, and meta-analyses showing step count benefits plateau around 7,000–8,000 steps/day, with some additional benefit up to 16,000 but interacting with age. He and Siim emphasize that walking offers unique mental benefits: it puts you in a 'task negative' state conducive to creativity, and when done outdoors in daylight, it anchors circadian rhythms and boosts mood. Greg recommends post-prandial walks of 15 minutes to meaningfully improve blood glucose responses. For those already doing intense training, step count becomes less critical, but for sedentary individuals, it's the starting point.