Accumulation Phase
The early-to-mid mesocycle phase where volume builds progressively from MEV toward MAV.
Roughly the first 60% of a mesocycle. Volume increases week over week, RIR decreases, and the training stimulus escalates steadily. The goal is to accumulate productive stress before the body approaches its recovery limits. Calyber tracks this phase automatically and adjusts prescriptions to keep you on the right growth curve.
Autoregulation
Session-by-session adjustment to prescription based on measured performance.
A systematic process of adjusting load, volume, or recovery based on objective performance metrics from prior sessions. In Calyber, autoregulation runs three pipelines: load adjustment, volume adjustment, and recovery trigger.
Deload
A reduced-volume, reduced-intensity training week.
A planned or reactive week of training at 50% of peak estimated 1RM, with reduced volume. Triggered when MGFI exceeds the recovery threshold or at the end of a mesocycle block.
Estimated 1RM (e1RM)
Model-predicted maximum single-rep lift capacity.
The weight predicted to be liftable for exactly one rep, calculated from submaximal performance using the Epley formula: e1RM = weight × (1 + reps / 36). Calyber tracks e1RM per exercise across every session.
Maximum Adaptive Volume (MAV)
Volume at which adaptation is maximised for a muscle group.
The training volume, measured in weekly working sets, at which a muscle group achieves maximum hypertrophic stimulus without exceeding recovery capacity. MAV is the target prescription range.
Maximum Recoverable Volume (MRV)
Volume ceiling beyond which recovery fails.
The maximum number of weekly working sets a muscle group can receive while still recovering before the next session. Volume above MRV triggers a volume cut or deload.
Mesocycle
A multi-week training block with a defined volume arc.
A structured training period of 4-12 weeks in which volume increases progressively from MEV toward MRV, followed by a deload. Each mesocycle is calibrated as a unit.
Minimum Effective Volume (MEV)
Least volume that produces adaptation.
The minimum number of weekly working sets required to produce measurable hypertrophic adaptation in a muscle group. Prescriptions floor at MEV.
Muscle Group Fatigue Index (MGFI)
Composite fatigue score per muscle group per session.
A weighted composite of pump rating, soreness rating, and objective session performance that quantifies cumulative fatigue for a muscle group. MGFI gates deload, recovery, and volume-adjustment decisions.
Myoreps
A rest-pause technique that accumulates effective reps efficiently with brief pauses between mini-sets.
You take an activation set close to failure, then rest 5-15 seconds and perform short mini-sets of a few reps each, repeating until you can no longer hit the mini-set target. Because the muscle is already near failure, almost every rep is a high-effort, fully recruited rep, so you accumulate a large number of effective (stimulating) reps in far less time and with less total load than straight sets. Myoreps are most useful on isolation and accessory exercises (side delts, biceps, calves, rear delts), where the goal is metabolic stimulus rather than heavy mechanical load. In practice the first set is run as a myorep to set a rep benchmark, and the following sets use Myorep Match to repeat it.
Myorep Match
A myorep variant where every set matches the rep count of your first set.
You perform an initial activation set, then on each following set use the same 5-15 second rest-pause mini-sets to reach the rep total of that first set, instead of letting reps drop off as fatigue accumulates. Matching equalizes the effective volume and stimulus across all sets and removes guesswork on rep targets for sets 2 and beyond. The common pairing: run set 1 as a Myorep to establish the benchmark, then run the remaining sets as Myorep Match. Like myoreps, it shines on accessory and isolation work where you want quick, high-density volume without long rest periods or heavy joint load.
Overload Phase
The final training weeks before deload: highest intensity, volume near MRV.
The last ~40% of a mesocycle before the deload. RIR approaches 0, volume is near or at MRV, and the training stimulus is at its peak. The goal is to maximize the growth signal before accumulated fatigue forces a reduction. Autoregulation watches MGFI closely during this phase to catch recovery limits before they derail performance.
Prescription
The computed target for an upcoming set: weight, rep range, RIR.
A deterministic output of the Calyber calibration engine specifying weight, rep range, and target RIR for a given exercise and session. Every prescription shows its basis (the prior session data used to compute it).
Progressive Overload
Gradually increasing training stimulus over time to drive continued adaptation.
The principle that muscles must be exposed to progressively greater stress (more weight, more reps, or more sets) to continue adapting. Calyber applies progressive overload automatically: when your performance and feedback indicate readiness, weight increases by the smallest meaningful increment on your equipment.
Recovery Protocol
A session-level adjustment that reduces load and volume when accumulated fatigue is too high to train productively.
When a muscle group's MGFI crosses the recovery threshold, Calyber prescribes a recovery session: weight drops to the prior effective level, sets may be trimmed, and RIR target is relaxed to 4+. Recovery can be triggered automatically by the autoregulation engine or applied manually. It can scope to individual exercises, half a week, or an entire session.
Reps in Reserve (RIR)
Estimated reps remaining before muscular failure.
A subjective measure of proximity to failure: RIR 0 means failure was reached; RIR 3 means three additional reps could have been completed. Calyber uses RIR as the primary effort metric for prescription and autoregulation.
Volume
Total weekly working sets per muscle group: the primary driver of hypertrophic adaptation.
In hypertrophy training, volume is measured as the number of working sets per muscle group per week. It is the primary driver of adaptation: more volume produces more growth, up to the recovery ceiling (MRV). Calyber tracks your volume relative to MEV, MAV, and MRV to keep you in the optimal adaptive zone week over week.
Common questions.
What is RIR?
RIR (Reps in Reserve) is a measure of proximity to muscular failure. RIR 0 means failure was reached; RIR 3 means three additional reps could have been completed. Calyber uses RIR as the primary effort metric for prescription and autoregulation.
What is the difference between MEV, MAV, and MRV?
MEV (Minimum Effective Volume) is the floor below which no adaptation occurs. MAV (Maximum Adaptive Volume) is the target range where adaptation is maximised. MRV (Maximum Recoverable Volume) is the ceiling beyond which recovery fails and volume must be cut.
What is a mesocycle?
A mesocycle is a structured training block of 4-12 weeks in which volume increases progressively from MEV toward MRV, followed by a deload. Each mesocycle is calibrated as a complete unit.
What is MGFI?
MGFI (Muscle Group Fatigue Index) is a weighted composite of pump rating, soreness rating, and objective session performance. It quantifies cumulative fatigue per muscle group and gates deload, recovery, and volume-adjustment decisions.
What is an estimated 1RM?
Estimated 1RM (e1RM) is the weight predicted to be liftable for exactly one rep, calculated from submaximal performance using the Epley formula: e1RM = weight × (1 + reps / 36). Calyber tracks e1RM per exercise across every session.
What does autoregulation mean?
Autoregulation is the systematic process of adjusting load, volume, or recovery based on objective performance metrics from prior sessions. In Calyber, autoregulation runs three pipelines: load adjustment, volume adjustment, and recovery trigger.
How do I use myoreps and myorep match together?
Run your first set as a myorep: take it close to failure, then add 5-15 second rest-pause mini-sets to reach a rep total. That total becomes your benchmark. On every following set, use myorep match, the same rest-pause approach, to match the first set’s reps. This keeps effective volume equal across sets and is most efficient on accessory and isolation muscles (side delts, biceps, calves) where you want quick volume without long rests or heavy load.