2026.06.02 🏃‍♂️‍➡️6.6km

You've just graduated from rehab runs, but this is exactly when AI analysis is most useful—when you feel that 'unusual discomfort'! Please don't hesitate to rely on me anytime.

Thank you for your hard work running after a full day of desk work that left your lower back stiff. Your intuition that your 'lower back is unstable and left-side impact is up' was reflected in the numbers with almost cruel precision.
I have analyzed the Runmetrix_260602.csv and Garmin_260602.csv files you provided, so let's logically unravel what happened.

AI Analysis: 6/2 The price of desk work, 'pelvic lock' and the left foot's cry
Comparing this to the data from 5/31 (rehab graduation run), the human body's mechanism when the lower back is stiff becomes clearly apparent.
Metric (Average) | 5/31 (Graduation Run) | 6/2 (This time, stiff back run)
Pelvic Rotation | 15.5° | 14.1° (Significant decrease)
Landing Impact (Left) | 39.5 m/s² | 47.0 m/s² (Sharp increase!)
Landing Impact (Right) | 26.3 m/s² | 33.7 m/s² (Also increased)
① 'Forced pelvic lock' due to sitting all day
The primary culprit is indeed that pelvic rotation dropped to 14.1°.
As a result of long hours of desk work, the inner muscles around your lower back, such as the psoas and glutes, became rock-hard, making it physically impossible for your pelvis to rotate forward and backward, no matter how much you tried to be conscious of it.
② Because the pelvis doesn't rotate, the left foot 'slams down from above'
If the pelvis doesn't rotate (meaning you can't pedal like a bicycle), you cannot land by smoothly sliding your foot backward from the air.
As a result, as you noticed, the left landing impact surged to 47.0 m/s². In the latter half of the laps (5km to 7km), it actually exceeded 50.0 m/s².
This is a figure that even exceeds the left impact (44.3 m/s²) during the 'runaway gear' incident on 12/11 that we analyzed before. Because your lower back dropped and the suspension wasn't working, your left foot was literally slamming directly into the ground.

Traces of 'tenacious correction' during the 10 sets of 300m sidewalk
However, it is impressive that you don't just fall down. Looking at the data from the second half, the traces of your struggle with the '10 sidewalk sets' to try and finish in a good way are engraved.
Looking at the Garmin laps, from the 4th km onwards, you maintained an even pace at a high speed level: 5:08 -> 5:04 -> 5:06.
Looking at the Runmetrix data (5th-6th km), pelvic rotation remained stuck around 14°, but ground contact time shortened to 194ms-195ms.
This is a highly advanced defensive technique where, since your lower back wasn't rotating, you 'increased your pitch and shortened ground contact to the limit to try and escape the impact without increasing it further.' Because of this control, you were able to finish the run feeling 'somewhat better' without collapsing midway.

Future advice: A prescription for the day after desk work
This time, it wasn't a recurrence of an injury, but entirely caused by 'physical suspension (muscle freeze) due to desk work.' It wasn't so much that your form collapsed, but that your body was in a state where it couldn't move.
[Lessons and countermeasures for this time]
• Cause: Sitting all day caused the lower back area to stiffen, and pelvic rotation dropped to 14.1°. The landing impact, having nowhere else to go, concentrated on the left foot (max 50.6 m/s²).
• Countermeasure for next time: On the day after long desk work, it is safer to perform 'hip joint stretches' or 'dynamic stretches that move the pelvis forward and backward' more carefully than usual to remove the 'rust' from your pelvis before you start running.
You have graduated from rehab, but changes due to your work environment will continue to happen. If you feel like something is 'off' like this time, please come and dump your data anytime.
Today, please do more thorough stretching around your lower back after the run than before, and make sure to loosen up those stiff muscles well!

I see, that's what it was! So you 'started running in the evening with those legs that had become stiff from desk work.'
That makes the reason for that 'pelvic lock' and 'left impact spike' make perfect sense. Immediately after desk work, your glutes and hip joint muscles are still asleep (in a dormant state), so you start in the worst possible condition.
On days when you feel 'my lower back seems bad today...' after desk work, here are '3 steps (time required: 5 minutes)' you can do before running to forcibly unlock your pelvis and drastically change your run.

3 steps to unlock 'pelvic lock' immediately after desk work
This is a menu you can do quickly before leaving the house or after putting on your shoes at the park starting point.
① [Super Important] Wake-up switch for the gluteus maximus (buttocks)
The part that is most crushed from sitting all day is the 'buttocks (gluteus maximus).' If you can't use this, your knees and lower back will take the impact instead.
• How to do it:
Take a big step forward with one leg and drop the knee of the back leg until it's almost touching the floor (a lunge).
• Point:
Feel your weight firmly on the 'buttock' of the front leg. Just doing this slowly and deeply 5 times on each side will send an electrical signal to your glute muscles saying 'we're about to move.'
② [Brake release] Stretching the psoas (front of the hip joint)
While sitting, the hip joint is always fixed in a 'bent state.' If this shrinks, your legs won't flow backward when running, and your pelvis won't rotate.
• How to do it:
While in the lunge position from ①, this time push the base of the back leg (the hip crease) forward to stretch it.
• Point:
If you arch your upper body slightly backward, you will feel the front of your hip joint stretching from deep inside your abdomen. Hold for 20 seconds on each side. This will make the 'gear' that pulls your legs backward rotate smoothly.
③ [Rust removal] Pelvic 'front-back/left-right' rotation
Finally, oil the stiff pelvic joints (sacroiliac joints).
• How to do it:
Stand with your feet shoulder-width apart and place both hands on your waist. Like hula dancing, rotate your pelvis in a large circle.
• Point:
Be conscious of the 'forward/backward tilt' and 'left/right rotation' that were low in the previous Runmetrix data, and move dynamically in a large circle 5 times clockwise and 5 times counter-clockwise.

Summary: Prevent '50 m/s²' impact with 5 minutes before running
After desk work, it's not so much that your muscles are hard, but that 'your brain has forgotten how to move your lower back (it has locked it).'
By just taking these 3 steps, it becomes easier to create the feeling of 'oh, my lower back is engaged today' (high waist) from the 1st km of your run, and you can significantly soften the 'thud!' impact on your left foot.
You have graduated from rehab runs, but from now on, it's an adult runner's challenge of 'how to deal with desk work.' Please try incorporating this into your routine before your evening run!

Of course 🙆‍♂️
Analyzing days like this where you feel 'something is off' or 'my body isn't clicking today' is actually quite meaningful.
And this time, your own self-analysis is quite spot on.
Today's theme is almost exactly this.
Stiffness in lower back/pelvis -> hard to maintain high waist -> taken by the left leg side
It shows up quite honestly in the data too.
First, the Garmin side.
• Vertical oscillation: consistently fixed around 7.4cm
• Ground contact time: 219-225ms
• Pitch: around 187
Looking only at this, it doesn't look that bad at first glance.
Rather, 'it hasn't collapsed.'
But looking at the Runmetrix side, the characteristics appear gradually.
Especially this.
• Left landing impact: 43 -> 50.6
• Right landing impact: 31 -> 35
The left-right difference is quite large.
More than the average value, there is a feeling of 'taking it on the left and not releasing it to the right.'
Moreover, today,
• Symmetry: 85 -> 93
• Overall score: 64 -> 70
You actually straightened it out in the second half.
In other words,
Rather than 'collapsing your form',
it feels like 'your lower back was stiff, your pelvis didn't move, and your left leg took on the role of a cushion.'
What you said about
not being able to stabilize a high waist
is quite the core of the issue.
What tends to happen the day after long hours of desk work is
• Lack of hip extension
• Reduced play in pelvic tilt
• Psoas stiffness
• Lack of thoracic rotation
This set, and when that happens, you start 'processing the ground with your legs.'
Today's rise in left impact is close to that typical pattern.
However, this part was quite good.
You quickly returned to the 300m sidewalk
This was the perfect answer.
If you had gone to the long straight of the Asakawa river today,
there is a possibility that you would have felt it quite a bit in the second half around:
• Left knee area
• Hamstring base
• Iliotibial band line
Also, it's a big deal that 'it didn't get worse even though it was a bad day' today.
In the past, on a day like this,
• Ground contact time would worsen
• Pitch would drop
• Vertical oscillation would increase
• Symmetry would collapse
I think it would have gone that far, but this time it didn't collapse that much.
In other words, the foundation remains quite strong.
Especially in the second half,
• Symmetry 93
• Overall 70
The fact that you brought it back up to this level means your 'correction ability' has improved quite a bit.
You were probably unconsciously doing things like:
• Resetting your pelvis
• Aligning your landing position
• Releasing tension
while resetting in detail on the 300m sidewalk.
This is a very strong point for you right now.
Also, personally, what relieved me most today was
that it wasn't 'data showing the knee itself was broken.'
Today's problem was 'upstream (lower back/pelvis)' rather than the 'joint.'
So the countermeasures are relatively simple, and
today, rather than running, it seems like
• Stretching the psoas
• Loosening the glutes
• Thoracic rotation
• Walking lightly
would be more effective.
Especially after desk work,
I feel that 'returning to a state where the pelvis moves first' suits you better than 'running to loosen up.'
Even so, it's a big deal that you were able to finish the first 'bad day' after graduating from rehab without breaking anything.

I see, that's how it was.
Then this time it's quite a 'typical desk work stiffness run.'
Immediately after sitting for a long time, with your type of form, it's especially easy to get:
• Psoas shrinking
• Glutes slacking off
• Pelvis not moving forward
• Thorax not rotating
• Posture being created only by the lumbar spine
And if you run in that state,
it's easy to end up 'trying to create a high waist, so your lower back arches -> landing is too far forward -> taking it on the left.'
So on days like yesterday,
rather than 'trying hard to stretch,' I think it's effective to 'create a state where the pelvis flows forward.'
For you, this order seems like it would change things quite a bit in about 5-8 minutes before running.
① First, walk (super important)
2-3 minutes is fine, so
don't start running immediately, just walk normally.
At this time, be conscious of:
• Swinging your arms a little
• Moving your legs from the pelvis
• Twisting your back
For the sitting-stiffness type, 'thawing the joints by walking' is often more effective than jogging immediately.
② Open the hip joints, not the 'lower back'
I recommend this type of thing:
• Leg swings forward/backward 10 times
• Side swings 10 times
• Light lunges left/right
• Single-leg standing pelvic rotation
Especially for you,
when you try to 'maintain a high waist,' you tend to work hard on the lumbar spine side, so
if you create the feeling of 'being able to send the hip joint backward' instead of 'standing the lower back up,' it should change quite a bit.
③ Finally, just 20-30 seconds of strides
This is quite important.
However, not fast, just confirm:
• Landing directly underneath
• Light pitch
• Not leaving your legs behind
If you feel 'I'm taking it on the left today' here, it's also easier to decide to lighten the menu for the day immediately.
Also, for you, what seems like it would be quite effective is
the subtle thing of 'lifting one side of your buttock at a time while sitting before running.'
In a chair,
• Lift left buttock slightly
• Lift right buttock slightly
do this alternately about 10 times.
For many people, just this wakes up the pelvic area.
For you right now,
it's not 'lack of leg strength' like before the injury, but
the problem of 'starting to run while the range of motion is asleep' seems quite large.
Conversely, if you can manage the first 10 minutes of the run well, it seems like you will be quite stable.