Shoulders and arms: the muscles, the exercises

01The short answer

02The shoulder: deltoid and rotator cuff

According to Cleveland Clinic, the deltoid helps you move your arm in different directions and stabilizes the shoulder joint. It has three parts:

• the front (anterior deltoid), which helps move the arm forward;
• the side (lateral deltoid), which helps move it out to the side, as well as up and down;
• the back (posterior deltoid), which helps move it backward.

The rotator cuff brings together four muscles: supraspinatus, subscapularis, infraspinatus and teres minor. It holds the humerus, the upper arm bone, in its socket, and keeps the shoulder stable during movement. You use it to raise your arm overhead, hold it out from your side and rotate it toward or away from your body. Cleveland Clinic advises warming up before activity and cooling down after, and stopping as soon as pain appears, never pushing through it.

03The arm: biceps, brachialis, triceps

StatPearls adds a detail: the biceps is mainly a strong supinator of the forearm, meaning it turns the palm up, and a weaker elbow flexor; the main muscle that bends the elbow is the brachialis. At the back of the arm, the triceps' primary role is to extend the forearm at the elbow. In karate, that same movement straightens the arm in a punch.

04Three simple exercises

• Wall push-ups. The NHS describes them this way: stand at arm's length from the wall, place your hands flat on the wall at chest height, fingers pointing up; with your back straight, slowly bend your arms to bring your body toward the wall, keeping your elbows close to your sides, then slowly return. Aim for 3 sets of 5 to 10 repetitions.
• Biceps curls. From the same page: hold light weights (filled water bottles will do), feet hip-width apart, arms by your sides; slowly bend your arms until the weight reaches your shoulder, then slowly lower them. Aim for 3 sets of 5 repetitions with each arm; it can also be done sitting.
• Shoulder blade squeeze. In its back routine, Mayo Clinic suggests sitting up straight on a chair without armrests, pulling your shoulder blades together, holding for 5 seconds, then relaxing; 3 to 5 times, twice a day.

The NHS advises doing its strength exercises, such as wall push-ups and curls, at least twice a week, building up the repetitions gradually.

05How many times a week?

The Canadian 24-Hour Movement Guidelines recommend that adults do muscle-strengthening activities using the major muscle groups at least twice a week. The American College of Sports Medicine advises leaving at least 48 hours between two sessions for the same muscle group. Build muscle and lose fat explains why muscle matters for women.

06Strength, at the noon class

Joanie Roussy's women's classes, at noon on weekdays, get you moving in a group: Strong Nation™ syncs cardio and strength to music, with no equipment; Bootcamp moves you from station to station, with and without equipment; Zumba® gets you dancing. Joanie also offers private, personalized 60-minute training sessions on request. Adult karate, mixed and open from age 14, runs in the evening.

07At the office, in Griffintown or Pointe-Saint-Charles

The shoulder blade squeeze is done sitting, on a chair without armrests: a break you can take at the office, in Griffintown or Pointe-Saint-Charles, between tasks. From Le Sud-Ouest, getting to the dojo works out the route to 550 chemin du Golf, suite 010, on Nuns' Island, and the schedule gives the class days.

Sources

1. Cleveland Clinic, “Deltoid Muscles” (2021) — my.clevelandclinic.org/health/body/21875-deltoid-muscles
2. Cleveland Clinic, “Rotator Cuff” (2023) — my.clevelandclinic.org/health/body/rotator-cuff
3. StatPearls, “Anatomy, Shoulder and Upper Limb, Biceps Muscle” — www.statpearls.com/point-of-care/18251
4. Tiwana, Sinkler and Bordoni, StatPearls, “Anatomy, Shoulder and Upper Limb, Triceps Muscle” (2023) — www.ncbi.nlm.nih.gov/books/NBK536996/
5. NHS, “Strength exercises” (2024) — www.nhs.uk/live-well/exercise/strength-exercises
6. Mayo Clinic, “Back exercises in 15 minutes a day” (2026) — www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/back-pain/art-20546859
7. CSEP, Canadian 24-Hour Movement Guidelines, adults 18–64 (2020) — csepguidelines.ca/guidelines/adults-18-64/
8. Garber et al., American College of Sports Medicine position stand, Med Sci Sports Exerc (2011) — doi.org/10.1249/MSS.0b013e318213fefb

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