Learn Hardcore Japanese: kodomo no koro ni supootu no naraigoto toka ongaku no naraigoto toka wo suru to, syuutyuuryoku ya tairyoku ga sizen ni mi ni tuku to iwarete imasu. - It’s said that if children do sports lessons, music lessons, and so on, they naturally gain concentration and physical strength.

子供のころに literally means “at the time when (one is) a child”, so in natural English: “when (you / I / people) are children” or “in childhood”.

ころ and とき are very close in meaning; both can mean “time (period)”.
子供のころ(に) and 子供のとき(に) are both correct and very common.

Nuance:

ころ often feels a bit like a vague period: “around the time when I was a child”.
とき can be slightly more neutral / precise: “at the time when I was a child”.

In this sentence, there’s no big difference in meaning; you could replace 子供のころに with 子供のときに and it would still sound natural.

Why is the particle に used after 子供のころ?

Here に marks a point or period in time:

子供のころに = “at the time when one is a child / during childhood”.

In Japanese, に is commonly used:

after specific times:
- ３時に行きます – I’ll go at 3 o’clock.
and also with more general time expressions:
- 夏に海へ行きます – I go to the sea in summer.
- 子供のころにピアノを習いました – I took piano lessons when I was a child.

So 子供のころに is just “during (the period of) childhood”.

What does 習い事 mean in スポーツの習い事 and 音楽の習い事?

習い事（ならいごと） is a very common word in Japanese. It means:

“lessons / classes in some skill taken regularly outside of regular school”
(often as an extracurricular activity or hobby).

Typical 習い事:

ピアノ, バイオリン, ダンス, 水泳, サッカー, 書道, 英会話, etc.

So:

スポーツの習い事 = sports-related lessons (like swimming school, soccer school)
音楽の習い事 = music lessons (like piano, violin, etc.)

It’s more specific than just “doing sports” or “doing music”; it implies organized lessons / classes that you attend.

Why is it スポーツの習い事 and not just スポーツをする?

スポーツをする simply means “to play / do sports” in general.

スポーツの習い事 emphasizes that you:

are taking structured lessons,
probably with a teacher / coach,
and it’s a somewhat formal, ongoing activity (after-school classes, weekend lessons, etc.).

So:

子供のころにスポーツをすると…
→ when children play sports…
子供のころにスポーツの習い事をすると…
→ when children take sports lessons / are enrolled in sports classes…

The sentence is talking about enrolling kids in regular lessons, not just casually playing.

What is the role of とか in スポーツの習い事とか音楽の習い事とか? Why is it used twice?

とか after a noun is a casual way to say:

“things like ~”,
“~ and stuff”,
“~ or ~, for example”.

In スポーツの習い事とか音楽の習い事とか:

The first とか loosely connects スポーツの習い事 and 音楽の習い事:
- “sports lessons and things like that, music lessons and so on…”
The second とか at the end signals that the list is not complete:
- “…sports lessons, music lessons, and the like / etc.”

So the phrase suggests:

“When children do sports lessons, music lessons, and similar kinds of lessons…”

The repetition sounds natural in spoken or casual-style writing and emphasizes “these kinds of things, for example”.

Why is there an を before する after all the とか? How does とか work with the object particle?

The structure is:

スポーツの習い事とか音楽の習い事とかをする

You can think of it as:

[スポーツの習い事とか音楽の習い事とか] をする

So:

を is the object marker for する.
The とか items form one big noun phrase that is the object of する.

In other words:

“to do [things like sports lessons, music lessons, etc.].”

Only one を is needed at the end to cover the entire list formed with とか.

What does すると mean here, and what kind of “if/when” is this 〜と conditional?

In the sentence:

…習い事とかをすると、集中力や体力が自然に身につく…

する is the verb “to do”, and と here is a conditional particle, so すると means:

“if (you) do (them)” / “when (you) do (them)”.

The 〜と conditional often expresses:

a natural result or automatic consequence, like a rule or general tendency.

Examples:

春になると、暖かくなります。
When it becomes spring, it gets warm.
このボタンを押すと、ドアが開きます。
If you press this button, the door opens.

So in this sentence, 〜すると suggests:

If/when children do those kinds of lessons, as a natural result their concentration and physical strength develop.

It’s describing a general tendency, not a one-time event.

Why is や used in 集中力や体力が… instead of と?

Both AとB and AやB can translate as “A and B”, but the nuance is different.

AとB = A and B (only those two), a more closed list.
AやB = A and B (and possibly other similar things), a more open / non-exhaustive list.

So:

集中力と体力が自然に身につく
→ concentration and physical strength (specifically these two) develop.
集中力や体力が自然に身につく
→ concentration, physical strength, and things like that develop.

Using や matches the overall “examples” feel of the sentence (we already had とか earlier), suggesting not just these two abilities but similar ones as well.

What does 自然に身につく mean? How do 自然に and 身につく work grammatically?

Breakdown:

自然に（しぜんに）
- Adverb form of 自然 (natural).
- Means “naturally / without forcing it / as a matter of course”.
身につく（みにつく）
- Literally: “to attach to the body”.
- Idiomatic meaning: “to acquire (a skill, ability, habit) so that it becomes part of you”,
  i.e. to really master / internalize it.
- It’s intransitive (no direct object with を).

Compare:

身につく – “(a skill) is acquired / becomes part of you.”
身につける – “to acquire / master (a skill)” (transitive verb, takes an object with を).

So:

集中力や体力が自然に身につく
→ “Concentration and physical strength are naturally acquired / naturally become part of you.”

Grammatically:

自然に modifies 身につく (how they are acquired → “naturally”).
集中力や体力が is the subject marked by が.

Why is が used with 集中力や体力が instead of は?

Here 集中力や体力 are the things that develop / are acquired, so they are the grammatical subject of 身につく. が marks that subject.

集中力や体力が自然に身につく
→ “Concentration and physical strength (subject) are naturally acquired (verb).”

If you used は, you’d be putting a topic contrast or emphasis:

集中力や体力は自然に身につく。
“As for concentration and physical strength, they are acquired naturally (but maybe something else is not).”

In a neutral statement of “X (subject) happens,” が is natural.

What does 〜と言われています mean, and why is it in the passive form?

〜と言われています is a very common pattern meaning:

“It is said that ~”,
“People say that ~”,
“It is generally believed that ~”.

Breakdown:

言う = to say.
言われる = passive form → “to be said”.
言われています = progressive/present → “is being said / is said (in general, nowadays)”.
The と before it is the quotation particle, marking the content of what is said.

So:

…自然に身につくと言われています。
→ “It is said that concentration and physical strength are naturally acquired.”

The passive form 言われています is used because:

the speaker is not specifying who says it,
it presents the statement as general opinion / commonly held belief,
not the speaker’s personal claim.

Could we say 身につくと言います instead of 身につくと言われています? What would change?

You can grammatically say:

「子供のころに〜をすると、集中力や体力が自然に身につく」と言います。

But the nuance changes:

〜と言います usually implies a specific speaker or group (I say, they say, we say).
〜と言われています is more impersonal, suggesting:
- “It is generally said / widely believed that…”

Using 言われています is more natural when:

you’re presenting a general, widely accepted idea,
like in articles, explanations, textbooks, etc.

Using と言います would make the sentence sound more like:

“People say that…” but from a specific viewpoint (e.g. “In Japan, they say that…”), and you’d often want to specify who:
専門家はこう言います – Experts say this.
日本では、こう言います – In Japan, they say this.

So と言われています fits better for a neutral “this is what people say” tone.

Why does the sentence put the “if/when” part first and the “it is said that…” part at the end? Is this normal in Japanese?

Yes, this is very normal Japanese sentence structure.

The pattern is:

[Condition clause] と、[Result clause] と言われています。

Concretely:

子供のころにスポーツの習い事とか音楽の習い事とかをすると、
→ “If/when children do sports lessons, music lessons, etc.,”
集中力や体力が自然に身につくと
→ “(that) concentration and physical strength are naturally acquired”
言われています。
→ “it is said.”

Japanese often:

puts the “background information” or “condition” at the beginning,
and leaves the main verb (here, 言われています) to the very end.

So the overall natural flow in Japanese is:

When children do such lessons → concentration/strength naturally develop → it is said.

This “verb comes last” structure is a basic feature of Japanese grammar.