Learn Hardcore French: Selon leur médecin, faire un peu de sport chaque jour est très bénéfique pour le cœur. - According to their doctor, doing a bit of exercise every day is very beneficial for the heart.

Faire un peu de sport chaque jour is the grammatical subject of est.
Literally: "To do a bit of exercise every day is very beneficial for the heart."

Structure:

Selon leur médecin = According to their doctor (introductory phrase)
faire un peu de sport chaque jour = subject (an action in general)
est = verb
très bénéfique pour le cœur = predicate

You do not need de before faire here. It’s just:

Selon leur médecin, + [infinitive clause as subject] + est + ...

This construction is common in French:

Fumer est dangereux pour la santé. – Smoking is dangerous for your health.
Bien dormir est important. – Sleeping well is important.

Why is it leur médecin and not leurs médecins or son médecin?

In French, leur vs leurs depends on how many things are possessed, not how many people possess them.

leur médecin = one doctor belonging to several people (their one doctor)
leurs médecins = several doctors belonging to several people (their doctors, plural)

So:

Selon leur médecin implies they share the same doctor (or we’re talking about a single doctor for the group).
If each had their own different doctor and you wanted to insist on that, you might say selon leurs médecins, but this is less common and sounds more like you’re referring to a collection of doctors.

Why not son médecin?

son médecin = his/her doctor, referring to one person, not a group.
Here leur refers to a plural they.

Also, in French médecin is the normal word for doctor (as in medical doctor). Docteur is used in address (e.g. Bonjour, docteur) or in some expressions, but leur médecin is the most standard neutral phrasing here.

Could we say d’après leur médecin instead of selon leur médecin? What’s the difference?

Yes, you can say:

Selon leur médecin, ...
D’après leur médecin, ...

Both generally mean "according to their doctor", and in many everyday contexts they’re interchangeable.

Nuances (often subtle):

selon feels a bit more neutral/objective: according to what X says/thinks.
d’après sometimes carries a slight nuance of interpretation or report: based on what X says / judging from X.

In this sentence, both are fine and common:

Selon leur médecin, faire un peu de sport chaque jour est très bénéfique pour le cœur.
D’après leur médecin, faire un peu de sport chaque jour est très bénéfique pour le cœur.

No grammatical change is needed elsewhere in the sentence.

Why is it faire un peu de sport and not faire un peu du sport?

After quantity expressions like:

un peu (de) – a bit (of)
beaucoup (de) – a lot (of)
trop (de) – too much/many (of)
assez (de) – enough (of)

French uses de + noun, without an article:

un peu de sport
beaucoup de travail
trop de sucre
assez d’eau

So you must say:

un peu de sport, not un peu du sport

Compare:

faire du sport = to do (some) sport / to exercise (general habit; partitive du)
faire un peu de sport = to do a little sport (quantity un peu de
- noun)

The sentence uses un peu de to emphasize the small quantity of sport, so it must be de without an article.

What’s the difference between chaque jour and tous les jours?

Both often translate as "every day", but there is a nuance:

chaque jour
- Literally "each day"
- Slightly more formal/literary or a bit more individualizing: focusing on each separate day.
tous les jours
- Literally "all the days"
- Very common in spoken and informal French; emphasizes a habit or regularity.

In this sentence:

faire un peu de sport chaque jour = doing a bit of sport each day
faire un peu de sport tous les jours = doing a bit of sport every day (more colloquial)

Both are correct and natural; the choice is stylistic. The given sentence sounds a bit more neutral/formal with chaque jour.

Why is it est (singular) and not sont (plural)?

The verb est is singular because the subject is singular.

The subject is not sport or jours, but the whole infinitive phrase:

faire un peu de sport chaque jour = one single action or idea (doing a bit of sport every day)

In French, a clause or infinitive phrase used as a subject is treated as singular, so you use est:

Faire du sport est important.
Bien manger est essentiel.
Prendre des pauses régulières est utile.

So:

Faire un peu de sport chaque jour est très bénéfique pour le cœur.
Using sont would be ungrammatical here.

Why use bénéfique and not bon in this sentence?

Both are possible, but they don’t feel exactly the same.

bénéfique
- Means beneficial, good for you (in a health/well-being sense).
- More formal/technical; often used in medical or scientific contexts.
- Common collocation: bénéfique pour la santé / pour le cœur / pour l’organisme.
bon
- Very general adjective: good.
- You can say:
  - C’est bon pour le cœur.
  - C’est bon pour la santé.
- More everyday and less technical.

So:

est très bénéfique pour le cœur: sounds like a doctor’s statement, slightly more formal and precise.
est très bon pour le cœur: perfectly correct, more neutral/conversational.

The choice of bénéfique here matches the medical context (their doctor’s opinion).

Why is it pour le cœur and not pour ton cœur or au cœur?

Definite article with body parts

In French, when you talk in general about a body part (not a specific person’s), you usually use the definite article:

le cœur – the heart (in general)
les poumons – the lungs
la peau – the skin

So pour le cœur means "for the heart" in a general, universal sense (for people’s hearts, for the heart as an organ).

If you say pour ton cœur, that’s more specifically "for your heart", speaking directly to one person.

pour vs à / au

pour le cœur = beneficial for the heart, emphasizing benefit.
au cœur usually expresses location or impact:
- au cœur de = in the heart of
- avoir mal au cœur = to feel sick / nauseous (or sometimes heartache, context‑dependent)

So:

bénéfique pour le cœur is the standard expression for something that is good for the heart.
bénéfique au cœur is possible but less idiomatic; pour is much more natural here.

How is cœur pronounced, and what is that œ with a circumflex doing there?

Pronunciation:

cœur is pronounced approximately like "kur" in English, but with:
- a short, rounded eu sound (like in peur),
- and the final -r pronounced in the throat (French r).

Phonetically (IPA): /kœʁ/.

Spelling:

œ is a ligature of o and e, used in some French words: cœur, sœur, œuf, œuvre.
The ^ (circumflex) on ô or ê, etc., often indicates that there used to be an extra letter (often s) historically. In cœur, it reflects historical spelling changes, but for you as a learner, it mainly:
- affects spelling,
- does not change the basic modern pronunciation pattern compared to similar eur words like peur, heure.

So just remember:

cœur → same vowel sound as in peur and sœur.

Why is it très bénéfique and not beaucoup bénéfique?

In French, très and beaucoup don’t behave the same way:

très modifies adjectives and adverbs:
- très bénéfique
- très bon
- très intéressant
- parler très vite
beaucoup usually modifies verbs or quantity nouns:
- ça aide beaucoup – that helps a lot
- il travaille beaucoup – he works a lot
- beaucoup de sport – a lot of sport

You cannot say:

✗ beaucoup bénéfique (incorrect)

To intensify bénéfique, you must use très (or another adverb like vraiment, tellement, etc.):

est très bénéfique pour le cœur = is very beneficial for the heart.

Can selon leur médecin be placed elsewhere in the sentence?

Yes. Selon leur médecin is an introductory phrase giving the source of the information; it is quite flexible in position.

Possible placements:

At the beginning (as in the original):
- Selon leur médecin, faire un peu de sport chaque jour est très bénéfique pour le cœur.
In the middle, set off by commas:
- Faire un peu de sport chaque jour, selon leur médecin, est très bénéfique pour le cœur.
At the end:
- Faire un peu de sport chaque jour est très bénéfique pour le cœur, selon leur médecin.

All are grammatically correct. Differences are mostly about style and emphasis:

Beginning: neutral, common in written French.
Middle: slightly heavier, but can sound quite formal.
End: feels more like an afterthought or a clarification of whose opinion it is.