Fitness & Health Glossary

1

1RM (one-rep max)

The maximum load that can be lifted in a single complete repetition of an exercise. Used as a baseline for setting training load percentages.

A

Activity factor

A multiplier applied to BMR based on exercise level (sedentary to very active) to estimate total daily energy expenditure.

Anaerobic threshold

The exercise intensity at which the body accumulates lactate faster than it can clear it.

B

BAI (Body Adiposity Index)

An estimate of body fat percentage derived from hip circumference and height, without using body weight.

Basal metabolic rate (BMR)

The energy the body burns at complete rest just to maintain vital functions such as breathing and circulation.

BMI (Body Mass Index)

Body weight divided by height squared (kg/m²), used to classify underweight, normal weight, overweight, and obesity. Does not distinguish muscle from fat.

BMI WHO ranges

BMI cut-offs defined by the World Health Organization to classify underweight, normal weight, overweight, and obesity.

Body composition

The distribution of body weight between fat mass and lean mass (muscle, bone, water). A more precise indicator of health and fitness than weight alone.

Boer formula

A formula that estimates lean body mass from weight, height, and sex; considered one of the most accurate for this calculation.

Brozek equation

An alternative to the Siri equation for converting body density to body fat percentage, with a slight difference in the constant.

Brzycki formula

A popular formula for estimating 1RM from the weight lifted and the number of repetitions performed; tends to be accurate up to about 10 reps.

C

Cadence

The number of steps per minute while running. Values around 170–180 steps/min generally indicate a more efficient stride.

Calorie (kcal)

The unit of food energy. What a nutrition label calls a "calorie" is actually a kilocalorie (kcal): 1 kcal = 1,000 calories.

Caloric deficit

Consuming fewer calories than are expended. The necessary condition for weight loss.

Caloric surplus

Consuming more calories than are expended. Used for weight gain and, with training, muscle mass gain.

Carbohydrate

The macronutrient that is the body's primary source of quick energy, providing about 4 kcal per gram.

Casey Butt model

A model that estimates the limit of natural muscle development and maximum measurements (arm, chest, calf) from height and bone structure (wrists and ankles).

Chronotype

The body's natural tendency to sleep and be most active at certain times of day (morning, intermediate, or evening profile).

Circadian rhythm

The internal biological clock of approximately 24 hours that regulates sleep, temperature, hormones, and metabolism.

CKD-EPI 2021

The currently recommended equation for estimating glomerular filtration rate (GFR) from creatinine, age, and sex, without using race.

Classic physique

An aesthetic standard inspired by the golden era of bodybuilding, emphasizing harmonious proportions rather than maximum size.

Cockcroft-Gault

A classic formula that estimates creatinine clearance from age, weight, sex, and creatinine; widely used to adjust medication doses.

Compendium of Physical Activities (METs)

A scientific catalog assigning a MET value to hundreds of activities, the basis for estimating caloric expenditure for each exercise.

Cooper test

A test that estimates VO₂ max from the distance covered running at maximum effort for 12 minutes.

Creatinine

A substance produced by muscle metabolism and filtered by the kidneys; its blood level helps assess kidney function.

Creatinine clearance

A measure of the kidneys' ability to remove creatinine from the blood, used to estimate renal function.

Cunningham formula

A formula that estimates basal metabolic rate from lean body mass; considered accurate for individuals with substantial muscle mass.

D

Daniels-Gilbert (VDOT)

Jack Daniels' formula that converts race performance into the VDOT index, used to define ideal training paces.

Devine formula

A formula developed in 1974 to estimate ideal body weight from height and sex, originally intended for drug dosage calculations.

DOTS

A scoring system that succeeds Wilks, used to compare lifts from athletes of different body weights in powerlifting.

Due date (EDD)

The estimated date of delivery, generally 40 weeks (280 days) after the first day of the last menstrual period.

Durnin-Womersley

A protocol that estimates body density from four skinfold measurements (bicep, tricep, subscapular, and suprailiac).

E

Epley formula

A formula that estimates 1RM from the weight lifted and the number of repetitions performed; one of the most widely used.

F

Fat mass

The total amount of body fat in kilograms; complements lean mass in describing body composition.

Fat (lipid)

The most calorie-dense macronutrient (about 9 kcal per gram), essential for hormone production and vitamin absorption.

FFMI (Fat-Free Mass Index)

Fat-Free Mass Index: lean mass relative to height (lean mass ÷ height²), used to evaluate muscular development.

Fertile window

The days in the menstrual cycle with the highest probability of pregnancy, centered around ovulation.

Fiber

A type of indigestible carbohydrate that improves gut function and satiety without providing significant energy.

Fox formula (220 − age)

The traditional formula for estimating maximum heart rate by subtracting age from 220. Simple but less accurate than modern alternatives.

G

Gestational age

The duration of pregnancy counted in weeks, normally from the first day of the last menstrual period.

Gestational BMI

BMI calculated using pre-pregnancy weight, used to guide recommended weight gain during pregnancy.

Gestational trimester

The division of pregnancy into three phases of about 13 weeks each, with distinct developmental milestones for the baby.

Gestational weight gain

The recommended weight increase during pregnancy, which varies according to pre-pregnancy BMI.

GFR (glomerular filtration rate)

The volume of blood filtered by the kidneys per minute (mL/min/1.73 m²). The primary indicator of kidney function; values above 90 are generally considered normal.

Glycemic index

Measures how quickly a food raises blood glucose, on a scale of 0 to 100.

Glycemic load

Combines the glycemic index with the carbohydrate content of a serving, reflecting the actual impact of the food on blood sugar.

Gulati formula

A maximum heart rate formula specific to women: 206 − (0.88 × age).

H

Hamwi formula

A 1964 formula to estimate ideal body weight from height and sex, created for dietary calculations.

Harris-Benedict equation

The classic equation for estimating basal metabolic rate from weight, height, age, and sex.

Heart rate reserve

The difference between maximum heart rate and resting heart rate; reflects the margin available for exertion.

Hydration (water needs)

The amount of water the body needs per day, estimated from weight, activity level, and climate.

Hypertrophy

Increase in muscle fiber size in response to strength training and adequate protein and energy intake.

I

Ideal body weight

A weight range considered healthy for a given height, estimated by classic formulas or the BMI range of 18.5–24.9.

Ideal proportions

Ratios between body measurements (waist, shoulders, arms) considered aesthetically harmonious, such as the golden ratio of shoulders to waist.

IOM guidelines

Institute of Medicine recommendations for gestational weight gain based on pre-pregnancy BMI.

J

Jackson-Pollock protocol

A protocol that estimates body density from 3 or 7 skinfold measurements, then converted to body fat percentage using the Siri equation.

K

Karvonen method

Training zone calculation based on heart rate reserve and resting heart rate, offering a more individualized approach.

Katch-McArdle formula

A formula that estimates basal metabolic rate from lean body mass; ideal for those who know their body fat percentage.

KDIGO kidney disease stages

Classification of kidney function into stages (G1 to G5) based on glomerular filtration rate, standardized by KDIGO.

L

Lander formula

A formula that estimates 1RM from weight and number of repetitions, an alternative to Epley and Brzycki.

Lean body mass (LBM)

Everything in the body except fat: muscles, bones, organs, and water. The component of weight to preserve during a diet.

Lombardi formula

A 1RM estimation formula based on the weight raised to a power of the number of repetitions.

M

Macronutrients

Nutrients that provide energy in large quantities: proteins, carbohydrates, and fats.

Maintenance calories

The calorie level that maintains stable weight, equal to total daily energy expenditure.

Maximum heart rate

The highest number of beats per minute the heart reaches at maximum effort, estimated by age-based formulas.

Maximum strength

The greatest force a muscle or muscle group can produce in a single effort; trained with heavy loads and low repetitions.

Menstrual cycle

The period between the start of one menstruation and the start of the next, averaging 28 days, regulated by hormones.

MET (metabolic equivalent)

A multiple of resting energy expenditure (1 MET). An activity of 8 METs burns eight times more energy than sitting still.

Mifflin-St Jeor equation

Currently the most recommended equation for estimating basal metabolic rate from weight, height, age, and sex.

Miller formula

A formula to estimate ideal body weight from height and sex, an alternative to Devine and Robinson.

Muscle endurance

The ability of a muscle to sustain repeated efforts over time; trained with light loads and high repetitions.

N

Naegele's rule

A rule that estimates the due date by adding 7 days and 9 months to the first day of the last menstrual period.

Natural genetic potential

An estimate of the maximum muscle mass a person can achieve without external hormonal assistance.

Normalized FFMI

FFMI adjusted to a reference height of 1.80 m, allowing comparison between individuals of different statures.

O

Ovulation

The release of a mature egg from the ovary; the most fertile moment in the menstrual cycle.

P

Pace

Running speed expressed in minutes per kilometer (min/km). The most common way to measure running effort.

Percent body fat

The proportion of total weight that is fat, expressed as a percentage. Reflects body composition better than weight alone.

Percent of 1RM

Training load expressed as a fraction of 1RM (e.g., 80% of 1RM) to guide exercise intensity.

Powerlifting

A strength sport contested in three lifts: squat, bench press, and deadlift.

Powerlifting total

The sum of the highest valid loads in the three lifts (squat, bench press, and deadlift) in a competition.

Protein

A macronutrient made of amino acids, essential for building and repairing muscles; provides about 4 kcal per gram.

Protein requirement (g/kg)

The recommended amount of protein per kilogram of body weight per day, generally between 1.2 and 2.2 g/kg depending on goals.

R

Resting heart rate

The number of beats per minute with the body at complete rest; generally, the lower, the better the fitness level.

RFM (relative fat mass)

Relative Fat Mass: an estimate of body fat percentage calculated from height and waist circumference, without equipment.

Riegel formula

A formula that predicts finishing time at a running distance based on performance at another distance.

rMEQ questionnaire (Horne-Östberg)

The reduced version of the morningness-eveningness questionnaire used to identify a person's chronotype.

Robinson formula

A 1983 formula to estimate ideal body weight from height and sex, a refinement of the Devine equation.

Rockport walk test

A test that estimates VO₂ max from the time and heart rate when walking 1.6 km (one mile).

S

Siri equation

An equation converting body density to body fat percentage: %BF = (495 ÷ density) − 450.

Skinfold body density

Body mass per unit of volume, calculated from skinfold measurements and converted into body fat percentage.

Sleep cycle

A sequence of approximately 90 minutes of sleep phases (light, deep, and REM) that repeats several times during the night.

Sleep latency

The time it takes to fall asleep after lying down; very short or very long latency may indicate sleep problems.

Steve Reeves proportions

Ideal proportions proposed by actor and bodybuilder Steve Reeves, based on wrist and ankle circumferences.

Submaximal repetition

A repetition performed with a load below 1RM. Sets of multiple submaximal reps are used to estimate 1RM.

T

Tanaka formula

A modern maximum heart rate formula: 208 − (0.7 × age), more accurate than the traditional 220 − age.

TDEE (total daily energy expenditure)

Total calories burned per day, combining BMR with physical activity and digestion. The basis for planning weight loss or gain.

Time under tension

Total time a muscle remains under load during a set; influences the hypertrophic stimulus.

Training load (volume)

Total work in a session, generally sets × reps × load.

Training tonnage

The sum of all weight moved in a workout (sets × reps × load); a measure of total volume.

Training zones

Heart rate ranges corresponding to different intensities and goals, from light recovery to maximum effort.

U

US Navy method

A method that estimates body fat percentage from circumference measurements (neck, waist, and for women, hip) and height.

Uth formula

A formula that estimates VO₂ max from the ratio of maximum heart rate to resting heart rate.

V

VDOT

Jack Daniels' index that estimates a runner's level from race results, guiding ideal training paces.

Visceral fat

Fat accumulated around the internal organs of the abdomen, associated with higher cardiovascular and metabolic risk.

VO₂ max

The maximum volume of oxygen the body can absorb and use per minute; the primary measure of aerobic fitness.

W

Waist-to-height ratio (WHtR)

Waist circumference divided by height; values below 0.5 indicate lower cardiometabolic risk — a practical and reliable indicator.

Waist-to-hip ratio (WHR)

Waist circumference divided by hip circumference; indicates fat distribution and helps estimate cardiovascular risk.

Wilks coefficient

A factor that adjusts the load lifted by the athlete's body weight, allowing performance comparison across weight categories in powerlifting.

Woolcott-Bergman (RFM)

The study that proposed the RFM formula, estimating body fat percentage from height and waist circumference.