Can two people with different goals train together?

Yes, if the session is the same shape and the numbers are not. A shared workout only fails when one person does the other’s programme: the lifter on a strength block ends up doing a friend’s hypertrophy volume, or the beginner loads a bar to the experienced lifter’s weights. What has to be shared is the movement list and the order; what has to stay individual is the load, the reps in reserve, the rest, and the progression rule that decides next week. Get that split right and two different blocks can meet on a Tuesday without either being derailed. The same holds for a couple on opposite goals — one cutting, one gaining: the session can be shared, the food cannot, and a plan that writes both knows the difference. Rest between sets is individual too; the stronger partner usually needs more of it.

How does Liftor’s Blend write one session for two plans?

It looks at what both of your days can share. If one of you is on legs and the other on upper body it says so and leaves the days alone; where the two days overlap it writes one session from the lifts both can use, and then prescribes each lift twice — your weight, reps and rest from your own history, and your partner’s from theirs. Neither of you did the arithmetic. Afterwards the session is folded back into both plans as if each of you had trained your own, so the next week’s progression on each side is unaffected.

What does a training partner get to see?

By default a friend you have accepted sees your recent workouts, including the weight and reps of your best set for each exercise, your records, your streak and whether you skipped a day. Comparisons between friends are set to “volume only”, and your bodyweight stays private. Each of those can be switched off on the Privacy screen, reached from the Social tab. There is no feed and nothing is posted; a Blend is an invitation between two people, accepted by the second one, and the leaderboard that exists ranks strength, not attendance.

Does training with a partner make you work harder?

Yes, and the effect has a name and a century of measurement behind it. The Köhler effect is the finding that the less capable member of a pair performs a hard task better beside a partner than alone. Feltz, Kerr and Irwin tested it in 2011 with a series of planks held beside a partner who was always a little more capable and only present on a screen: people persisted significantly longer in every partner condition than on their own, whether or not the pair’s score depended on them. A year later Irwin and colleagues put fifty-eight women on stationary bikes over six sessions and found the same thing with bigger numbers — about 22 minutes with a partner whose result depended on theirs, about 20 beside a partner working independently, and about 11 alone.

The partner does not have to be in the room, and the partner has to be slightly better than you. A shared session in Liftor is built on that shape: the two of you do the same list in the same order, the loads are your own, so the stronger partner is a pace rather than a standard, and the comparison the app shows afterwards is volume — that you both did the work, which is the finding in one line.

How do you train together when one of you is much stronger?

Share the bar, not the plates. The list is the same, the loads are separate, and the stronger lifter usually needs more rest between sets — heavier work costs more recovery — so the pair’s rhythm is set by the slower clock rather than the faster one. Spot each other only on loads the spotter could hold. Above that, squat in a rack with the safety arms set just below depth, and bench with the safeties set or a second spotter; a weaker lifter should not be the spotter on a stronger lifter’s heavy squat or bench. Spotting is a job, not a courtesy, and between two people close enough in strength it is the reason the pair beats two solo sessions on the lifts that need a spotter. Change plates once, not twice: a good pair writes the loads out before the first set.

Blend prescribes every shared lift twice, at each person’s own weight, reps and rest, from each person’s own history, and it writes the rest as two timers rather than one. Nobody has to know the other’s numbers to follow the session; what a friend can see afterwards is covered above.

How does each person’s progress stay separate?

Because the session is folded back into two plans, not one. After a shared workout Liftor writes each person’s sets into their own history as if they had trained alone: the progression rule reads your top set and your reps in reserve, the estimated one-rep max updates from your loads, and next week’s numbers come from your block. Your partner’s block does the same with theirs. A pair in different phases — one in a push week, one in maintenance — can share a Tuesday without either plan noticing on Wednesday.

The food is never shared, because the goals are not: one of you cutting and one gaining is the ordinary case for a couple, and the daily plan writes two targets from two trends. The only thing the two plans have in common afterwards is the hour they were in the same room, which is the point.

Sources

Feltz DL, Kerr NL, Irwin BC. Buddy up: the Köhler effect applied to health games. Journal of Sport and Exercise Psychology, 2011; 33(4): 506–526
Irwin BC, Scorniaenchi J, Kerr NL, Eisenmann JC, Feltz DL. Aerobic exercise is promoted when individual performance affects the group: a test of the Köhler motivation gain effect. Annals of Behavioral Medicine, 2012; 44(2): 151–159
Liftor’s shared-session engine: one template, per-user weight, reps and rest (utils/sharedSessionOverload.ts in the app’s source)
Liftor’s sharing defaults and its Privacy screen: what an accepted friend sees, comparisons set to volume only (services/privacyService.ts and app/social/privacy-settings.tsx in the app’s source)